[XPU] fix_same_req_id

fastdeploy/engine/common_engine.py

@@ -2125,7 +2125,8 @@ def _process_allocate_resource_requests():
 
                 if not is_success:
                     if not self.enable_decode_cache_task:
-                        task.error_msg = "Not enough resources"
+                        if not task.get("error_msg", None):
+                            task.error_msg = "Not enough resources"
                         self.split_connector.send_cache_info_to_prefill([task])
                         self.llm_logger.warning(f"D has failed to send cache infos for task {task.request_id}")
                         processed_indices.append(idx)

fastdeploy/engine/sched/resource_manager_v1.py

@@ -1587,6 +1587,13 @@ def preallocate_resource_in_d(self, request: Request):
         ) // self.config.cache_config.block_size + self.config.cache_config.enc_dec_block_num
 
         with self.lock:
+            if request.request_id in self.requests:
+                llm_logger.warning(
+                    f"PD reschedule: request {request.request_id} already exists in D, "
+                    f"rejecting to avoid KV cache conflict"
+                )
+                request.error_msg = "Duplicate request id in decode"
+                return False
             if len(self.waiting) > 0:
                 return False
             if self.available_batch() == 0: