diff --git a/zerver/lib/markdown/__init__.py b/zerver/lib/markdown/__init__.py
index 0334f4c4bf..f934cb7884 100644
--- a/zerver/lib/markdown/__init__.py
+++ b/zerver/lib/markdown/__init__.py
@@ -1884,11 +1884,22 @@ class UserMentionPattern(markdown.inlinepatterns.InlineProcessor):
 
             wildcard = mention.user_mention_matches_wildcard(name)
 
-            id_syntax_match = re.match(r"(.+)?\|(?P<user_id>\d+)$", name)
+            # For @**|id** and @**name|id** mention syntaxes.
+            id_syntax_match = re.match(r"(?P<full_name>.+)?\|(?P<user_id>\d+)$", name)
             if id_syntax_match:
+                full_name = id_syntax_match.group("full_name")
                 id = int(id_syntax_match.group("user_id"))
                 user = db_data["mention_data"].get_user_by_id(id)
+
+                # For @**name|id**, we need to specifically check that
+                # name matches the full_name of user in mention_data.
+                # This enforces our decision that
+                # @**user_1_name|id_for_user_2** should be invalid syntax.
+                if full_name:
+                    if user and user["full_name"] != full_name:
+                        return None, None, None
             else:
+                # For @**name** syntax.
                 user = db_data["mention_data"].get_user_by_name(name)
 
             if wildcard:
@@ -2445,8 +2456,7 @@ def get_possible_mentions_info(realm_id: int, mention_texts: Set[str]) -> List[F
     if not mention_texts:
         return []
 
-    full_names = set()
-    mention_ids: Set[int] = set()
+    q_list = set()
 
     name_re = r"(?P<full_name>.+)?\|(?P<mention_id>\d+)$"
     for mention_text in mention_texts:
@@ -2455,15 +2465,15 @@ def get_possible_mentions_info(realm_id: int, mention_texts: Set[str]) -> List[F
             full_name = name_syntax_match.group("full_name")
             mention_id = name_syntax_match.group("mention_id")
             if full_name:
-                full_names.add(name_syntax_match.group("full_name"))
+                # For **name|id** mentions as mention_id
+                # cannot be null inside this block.
+                q_list.add(Q(full_name__iexact=full_name, id=mention_id))
             else:
-                mention_ids.add(int(mention_id))
+                # For **|id** syntax.
+                q_list.add(Q(id=mention_id))
         else:
-            full_names.add(mention_text)
-
-    q_list = {Q(full_name__iexact=full_name) for full_name in full_names}
-    id_q_list = {Q(id=id) for id in mention_ids}
-    q_list |= id_q_list
+            # For **name** syntax.
+            q_list.add(Q(full_name__iexact=mention_text))
 
     rows = (
         UserProfile.objects.filter(
diff --git a/zerver/tests/test_markdown.py b/zerver/tests/test_markdown.py
index 1bd4f59528..b84aa0b0db 100644
--- a/zerver/tests/test_markdown.py
+++ b/zerver/tests/test_markdown.py
@@ -1867,6 +1867,24 @@ class MarkdownTest(ZulipTestCase):
         )
         self.assertEqual(msg.mentions_user_ids, {user_profile.id})
 
+    def test_invalid_mention_not_uses_valid_mention_data(self) -> None:
+        sender_user_profile = self.example_user("othello")
+        hamlet = self.example_user("hamlet")
+        msg = Message(sender=sender_user_profile, sending_client=get_client("test"))
+
+        # Even though King Hamlet will be present in mention data as
+        # it was was fetched for first mention but second mention is
+        # incorrect(as it uses hamlet's id) so it should not be able
+        # to use that data for creating a valid mention.
+
+        content = f"@**King Hamlet|10** and @**aaron|{hamlet.id}**"
+        self.assertEqual(
+            render_markdown(msg, content),
+            f'<p><span class="user-mention" data-user-id="{hamlet.id}">'
+            f"@King Hamlet</span> and @<strong>aaron|{hamlet.id}</strong></p>",
+        )
+        self.assertEqual(msg.mentions_user_ids, {hamlet.id})
+
     def test_silent_mention_invalid_followed_by_valid(self) -> None:
         sender_user_profile = self.example_user("othello")
         user_profile = self.example_user("hamlet")