diff --git a/app_legacy/Helpers/database/forum.php b/app_legacy/Helpers/database/forum.php
index d9e82d22c3..78d7d060f4 100644
--- a/app_legacy/Helpers/database/forum.php
+++ b/app_legacy/Helpers/database/forum.php
@@ -268,6 +268,28 @@ function editTopicComment(int $commentID, string $newPayload): bool
     return false;
 }
 
+function getIsForumDoublePost(
+    int $authorID,
+    int $topicID,
+    string $commentPayload,
+): bool {
+    $query = "SELECT ftc.Payload, ftc.ForumTopicID
+        FROM ForumTopicComment AS ftc
+        WHERE AuthorID = :authorId
+        ORDER BY ftc.DateCreated DESC
+        LIMIT 1";
+
+    $dbResult = legacyDbFetch($query, ['authorId' => $authorID]);
+
+    $retrievedPayload = $dbResult['Payload'];
+    $retrievedTopicID = $dbResult['ForumTopicID'];
+
+    return
+        $retrievedPayload === $commentPayload
+        && $retrievedTopicID === $topicID
+    ;
+}
+
 function submitTopicComment(
     string $user,
     int $topicID,
@@ -278,6 +300,11 @@ function submitTopicComment(
     sanitize_sql_inputs($user);
     $userID = getUserIDFromUser($user);
 
+    if (getIsForumDoublePost($userID, $topicID, $commentPayload)) {
+        // Fail silently.
+        return true;
+    }
+
     // Replace inverted commas, Remove HTML
     $commentPayload = str_replace("'", "''", $commentPayload);
     $commentPayload = str_replace("<", "&lt;", $commentPayload);
diff --git a/app_legacy/Helpers/database/user-activity.php b/app_legacy/Helpers/database/user-activity.php
index 7c093720c9..950376929f 100644
--- a/app_legacy/Helpers/database/user-activity.php
+++ b/app_legacy/Helpers/database/user-activity.php
@@ -300,6 +300,25 @@ function RemoveComment(int $commentID, int $userID, int $permissions): bool
     return mysqli_affected_rows($db) > 0;
 }
 
+function getIsCommentDoublePost(int $userID, array|int $articleID, string $commentPayload): bool
+{
+    $query = "SELECT Comment.Payload, Comment.ArticleID
+        FROM Comment
+        WHERE UserID = :userId
+        ORDER BY Comment.Submitted DESC
+        LIMIT 1";
+
+    $dbResult = legacyDbFetch($query, ['userId' => $userID]);
+
+    $retrievedPayload = $dbResult['Payload'];
+    $retrievedArticleID = $dbResult['ArticleID'];
+
+    return
+        $retrievedPayload === $commentPayload
+        && $retrievedArticleID === $articleID
+    ;
+}
+
 function addArticleComment(
     string $user,
     int $articleType,
@@ -320,6 +339,11 @@ function addArticleComment(
         return false;
     }
 
+    if ($user !== "Server" && getIsCommentDoublePost($userID, $articleID, $commentPayload)) {
+        // Fail silently.
+        return true;
+    }
+
     // Replace all single quotes with double quotes (to work with MYSQL DB)
     // $commentPayload = str_replace( "'", "''", $commentPayload );