diff --git a/swh/web/api/views/identifiers.py b/swh/web/api/views/identifiers.py
--- a/swh/web/api/views/identifiers.py
+++ b/swh/web/api/views/identifiers.py
@@ -109,12 +109,13 @@
     # group swhids by their type
     swhids_by_type = group_swhids(swhids)
     # search for hashes not present in the storage
-    missing_hashes = set(
-        map(hash_to_bytes, archive.lookup_missing_hashes(swhids_by_type))
-    )
+    missing_hashes = {
+        k: set(map(hash_to_bytes, archive.lookup_missing_hashes({k: v})))
+        for k, v in swhids_by_type.items()
+    }
 
     for swhid in swhids:
-        if swhid.object_id not in missing_hashes:
+        if swhid.object_id not in missing_hashes[swhid.object_type]:
             response[str(swhid)]["known"] = True
 
     return response
diff --git a/swh/web/tests/api/views/test_identifiers.py b/swh/web/tests/api/views/test_identifiers.py
--- a/swh/web/tests/api/views/test_identifiers.py
+++ b/swh/web/tests/api/views/test_identifiers.py
@@ -140,6 +140,26 @@
     }
 
 
+def test_api_known_swhid_same_hash(api_client, content):
+    content_ = gen_swhid(ObjectType.CONTENT, content["sha1_git"])
+    # Reuse hash to make invalid directory SHWID
+    directory_ = gen_swhid(ObjectType.DIRECTORY, content["sha1_git"])
+
+    input_swhids = [
+        content_,
+        directory_,
+    ]
+
+    url = reverse("api-1-known")
+
+    resp = check_api_post_responses(api_client, url, data=input_swhids, status_code=200)
+
+    assert resp.data == {
+        content_: {"known": True},
+        directory_: {"known": False},
+    }
+
+
 def test_api_known_invalid_swhid(api_client):
     invalid_swhid_sha1 = ["swh:1:cnt:8068d0075010b590762c6cb5682ed53cb3c13de;"]
     invalid_swhid_type = ["swh:1:cnn:8068d0075010b590762c6cb5682ed53cb3c13deb"]