diff --git a/web/src/hooks/logic-hooks.ts b/web/src/hooks/logic-hooks.ts
index 1f7909016..25b2589ff 100644
--- a/web/src/hooks/logic-hooks.ts
+++ b/web/src/hooks/logic-hooks.ts
@@ -274,8 +274,17 @@ export const useSendMessageWithSse = (
                 const val = JSON.parse(value?.data || '');
                 const d = val?.data;
                 if (typeof d !== 'boolean') {
+
                   setAnswer((prev) => {
-                    let newAnswer = (prev.answer || '') + (d.answer || '');
+                    const prevAnswer = prev.answer || '';
+                    const currentAnswer = d.answer || '';
+
+                    let newAnswer: string;
+                    if (prevAnswer && currentAnswer.startsWith(prevAnswer)) {
+                      newAnswer = currentAnswer;
+                    } else {
+                      newAnswer = prevAnswer + currentAnswer;
+                    }
 
                     if (d.start_to_think === true) {
                       newAnswer = newAnswer + '<think>';