diff --git a/dspace-api/src/main/java/org/dspace/ctask/general/ItemMetadataQAChecker.java b/dspace-api/src/main/java/org/dspace/ctask/general/ItemMetadataQAChecker.java
index c4e5ef709b67..2f813b01f232 100644
--- a/dspace-api/src/main/java/org/dspace/ctask/general/ItemMetadataQAChecker.java
+++ b/dspace-api/src/main/java/org/dspace/ctask/general/ItemMetadataQAChecker.java
@@ -87,6 +87,7 @@ public void init(Curator curator, String taskId) throws IOException {
                     "dc.rights.label",
                     "dc.date.available",
                     "dc.source.uri",
+                    "dc.identifier.doi",
                     "metashare.ResourceInfo#DistributionInfo#LicenseInfo.license"
                 });
         strangeMetadata = configurationService.getArrayProperty("lr.curation.metadata.strange", new String[]{
diff --git a/dspace-api/src/main/java/org/dspace/identifier/DOIIdentifierProvider.java b/dspace-api/src/main/java/org/dspace/identifier/DOIIdentifierProvider.java
index dd48131b1fdf..ff5097aa5e5d 100644
--- a/dspace-api/src/main/java/org/dspace/identifier/DOIIdentifierProvider.java
+++ b/dspace-api/src/main/java/org/dspace/identifier/DOIIdentifierProvider.java
@@ -1067,13 +1067,26 @@ protected void saveDOIToObject(Context context, DSpaceObject dso, String doi)
         }
         Item item = (Item) dso;
 
-        itemService.addMetadata(context, item, MD_SCHEMA, DOI_ELEMENT, DOI_QUALIFIER, null,
-            doiService.DOIToExternalForm(doi));
-        try {
-            itemService.update(context, item);
-        } catch (SQLException | AuthorizeException ex) {
-            throw ex;
+        String doiURL = doiService.DOIToExternalForm(doi);
+
+        // Add the DOI to the metadata only if this exact value is not present yet. This keeps the operation
+        // idempotent (re-registration does not create duplicate values) without ever deleting metadata: a
+        // pre-existing, different DOI is left untouched. This method is called after the DOI has already been
+        // registered with the external agency, so destroying metadata here would be lossy and irreversible.
+        // Items that end up with more than one dc.identifier.doi value are surfaced by the ItemMetadataQAChecker
+        // curation task for manual review.
+        List<MetadataValue> existing = itemService.getMetadata(item, MD_SCHEMA, DOI_ELEMENT, DOI_QUALIFIER, Item.ANY);
+        boolean alreadyPresent = existing.stream()
+                .anyMatch(metadataValue -> doiURL.equals(metadataValue.getValue()));
+
+        if (alreadyPresent) {
+            log.debug("The DOI {} is already part of the metadata of Item {}. Not adding it again.",
+                    doi, item.getID());
+            return;
         }
+
+        itemService.addMetadata(context, item, MD_SCHEMA, DOI_ELEMENT, DOI_QUALIFIER, null, doiURL);
+        itemService.update(context, item);
     }
 
     /**
diff --git a/dspace-api/src/test/java/org/dspace/curate/ItemMetadataQACheckerIT.java b/dspace-api/src/test/java/org/dspace/curate/ItemMetadataQACheckerIT.java
index 315a04a68b11..446e5e809daf 100644
--- a/dspace-api/src/test/java/org/dspace/curate/ItemMetadataQACheckerIT.java
+++ b/dspace-api/src/test/java/org/dspace/curate/ItemMetadataQACheckerIT.java
@@ -63,6 +63,7 @@ public class ItemMetadataQACheckerIT extends AbstractIntegrationTestWithDatabase
     Item itemWithIncorrectLanguageName;
     Item itemWithTwoAvailableDates;
     Item itemWithTwoAvailableDatesAndLang;
+    Item itemWithTwoDois;
     Item itemVersion1;
     Item itemVersion2;
     Item itemVersion3;
@@ -146,6 +147,13 @@ public void setUp() throws Exception {
             itemService.addMetadata(context, itemWithTwoAvailableDatesAndLang,"dc", "date",
                     "available", "en_US", "2021-01-01");
 
+            itemWithTwoDois = ItemBuilder.createItem(context, collection)
+                    .withTitle("Item With Two DOIs")
+                    .withMetadata("dc", "type", null, "corpus")
+                    .withMetadata("dc", "identifier", "doi", "https://doi.org/10.5072/test-1")
+                    .withMetadata("dc", "identifier", "doi", "https://doi.org/10.5072/test-2")
+                    .build();
+
             itemVersion1 = ItemBuilder.createItem(context, collection)
                     .withTitle("Item Version 1")
                     .withMetadata("dc", "type", null, "corpus")
@@ -233,6 +241,20 @@ public void testItemWithTwoAvailableDatesAndLang() throws IOException {
         assertTrue("Result should mention multiple dc.date.available", result.contains("dc.date.available"));
     }
 
+    @Test
+    public void testItemWithTwoDois() throws IOException {
+        Curator curator = new Curator();
+        curator.addTask(TASK_NAME);
+        context.setCurrentUser(admin);
+
+        // Run curator task for item with two dc.identifier.doi - should fail
+        curator.curate(context, itemWithTwoDois.getHandle());
+        int status = curator.getStatus(TASK_NAME);
+        assertEquals("Curation should fail for item with two dc.identifier.doi", Curator.CURATE_FAIL, status);
+        String result = curator.getResult(TASK_NAME);
+        assertTrue("Result should mention multiple dc.identifier.doi", result.contains("dc.identifier.doi"));
+    }
+
     @Test
     public void testValidItem() throws IOException {
         Curator curator = new Curator();
diff --git a/dspace-api/src/test/java/org/dspace/identifier/DOIIdentifierProviderTest.java b/dspace-api/src/test/java/org/dspace/identifier/DOIIdentifierProviderTest.java
index 43f93e606dfd..7ef10de02311 100644
--- a/dspace-api/src/test/java/org/dspace/identifier/DOIIdentifierProviderTest.java
+++ b/dspace-api/src/test/java/org/dspace/identifier/DOIIdentifierProviderTest.java
@@ -23,6 +23,7 @@
 import java.util.Date;
 import java.util.List;
 import java.util.Random;
+import java.util.stream.Collectors;
 
 import org.apache.commons.collections4.CollectionUtils;
 import org.apache.commons.lang3.ObjectUtils;
@@ -332,6 +333,51 @@ public void testStore_DOI_as_item_metadata()
         assertTrue("Cannot store DOI as item metadata value.", result);
     }
 
+    @Test
+    public void testStore_DOI_keeps_existing_different_doi_metadata() throws SQLException, AuthorizeException,
+            IOException, IdentifierException, IllegalAccessException, WorkflowException {
+        Item item = newItem();
+
+        // this checks that the method does not fail if there is already a *different* DOI in the metadata,
+        // here we verify that the existing DOI is preserved (not deleted) and the new one is added alongside it.
+        // Items with more than one DOI are reported by the ItemMetadataQAChecker curation task, not silently
+        // cleaned up here.
+        String oldDoi = DOI.SCHEME + PREFIX + "/" + NAMESPACE_SEPARATOR + "1234";
+        String newDoi = DOI.SCHEME + PREFIX + "/" + NAMESPACE_SEPARATOR + Long.toHexString(new Date().getTime());
+
+        context.turnOffAuthorisationSystem();
+        itemService.addMetadata(context, item, DOIIdentifierProvider.MD_SCHEMA,
+                DOIIdentifierProvider.DOI_ELEMENT,
+                DOIIdentifierProvider.DOI_QUALIFIER,
+                null,
+                doiService.DOIToExternalForm(oldDoi));
+        provider.saveDOIToObject(context, item, newDoi);
+        context.restoreAuthSystemState();
+
+        checkDoiMetadata(item, oldDoi, newDoi);
+    }
+
+    @Test
+    public void testStore_DOI_check_single_doi_metadata() throws SQLException, AuthorizeException, IOException,
+            IdentifierException, IllegalAccessException, WorkflowException {
+        Item item = newItem();
+
+        // this checks that the method does not fail if there is already a DOI in the metadata,
+        // here we check if DOI metadata are not duplicated
+        String doi = DOI.SCHEME + PREFIX + "/" + NAMESPACE_SEPARATOR + Long.toHexString(new Date().getTime());
+
+        context.turnOffAuthorisationSystem();
+        itemService.addMetadata(context, item, DOIIdentifierProvider.MD_SCHEMA,
+                DOIIdentifierProvider.DOI_ELEMENT,
+                DOIIdentifierProvider.DOI_QUALIFIER,
+                null,
+                doiService.DOIToExternalForm(doi));
+        provider.saveDOIToObject(context, item, doi);
+        context.restoreAuthSystemState();
+
+        checkSingleDoiMetadata(item, doi);
+    }
+
     @Test
     public void testGet_DOI_out_of_item_metadata()
         throws SQLException, AuthorizeException, IOException, IdentifierException, IllegalAccessException,
@@ -868,4 +914,34 @@ public void testLoadOrCreateDOIReturnsMintedStatus()
     // registerOnline
     // reserveOnline
 
+    private void checkSingleDoiMetadata(Item item, String doi) throws IdentifierException {
+        List<MetadataValue> metadata = itemService.getMetadata(item, DOIIdentifierProvider.MD_SCHEMA,
+                DOIIdentifierProvider.DOI_ELEMENT,
+                DOIIdentifierProvider.DOI_QUALIFIER,
+                Item.ANY);
+        boolean result = false;
+        if (metadata.size() == 1 && metadata.get(0).getValue().equals(doiService.DOIToExternalForm(doi))) {
+            result = true;
+        }
+        assertTrue("Invalid or duplicate 'dc.identifier.doi' metadata value(s).", result);
+    }
+
+    private void checkDoiMetadata(Item item, String... dois) throws IdentifierException {
+        List<String> values = itemService.getMetadata(item, DOIIdentifierProvider.MD_SCHEMA,
+                        DOIIdentifierProvider.DOI_ELEMENT,
+                        DOIIdentifierProvider.DOI_QUALIFIER,
+                        Item.ANY)
+                .stream()
+                .map(MetadataValue::getValue)
+                .collect(Collectors.toList());
+
+        List<String> expected = new ArrayList<>();
+        for (String doi : dois) {
+            expected.add(doiService.DOIToExternalForm(doi));
+        }
+
+        assertEquals("Unexpected number of 'dc.identifier.doi' metadata values.", expected.size(), values.size());
+        assertTrue("Expected 'dc.identifier.doi' metadata values are missing.", values.containsAll(expected));
+    }
+
 }