diff --git a/IRaCIS.Core.Application/BusinessFilter/LegacyController/RequestDuplicationFilter.cs b/IRaCIS.Core.Application/BusinessFilter/LegacyController/RequestDuplicationFilter.cs
index 17c3b95eb..b1d0ac222 100644
--- a/IRaCIS.Core.Application/BusinessFilter/LegacyController/RequestDuplicationFilter.cs
+++ b/IRaCIS.Core.Application/BusinessFilter/LegacyController/RequestDuplicationFilter.cs
@@ -70,6 +70,10 @@ namespace IRaCIS.Core.Application.BusinessFilter.LegacyController
                     {
                         this.RequestDuplication();
                     }
+                    catch (BusinessValidationFailedException)
+                    {
+                        throw;
+                    }
                     catch (Exception)
                     {
                       
@@ -106,17 +110,14 @@ namespace IRaCIS.Core.Application.BusinessFilter.LegacyController
                         RequestTime = DateTime.Now
                     };
 
-                    IRCSystemInfo.RequestRecordList= IRCSystemInfo.RequestRecordList.Where(x => x.RequestTime >= DateTime.Now.AddSeconds(-RequestDuplicationOptionsMonitor.CurrentValue.CacheTimeSeconds)).ToList();
-
-                   
-                    var requestsTimes = IRCSystemInfo.RequestRecordList.Any(x=>
-                   x.RequestTime>= requestInfo.RequestTime.AddMilliseconds(-RequestDuplicationOptionsMonitor.CurrentValue.DuplicationWindowMs)&&
-                    x.RequestKey== requestInfo.RequestKey);
-                    if (requestsTimes)
+                    var isAdded = IRCSystemInfo.TryAddRequestRecord(
+                        requestInfo,
+                        RequestDuplicationOptionsMonitor.CurrentValue.CacheTimeSeconds,
+                        RequestDuplicationOptionsMonitor.CurrentValue.DuplicationWindowMs);
+                    if (!isAdded)
                     {
                         throw new BusinessValidationFailedException(_localizer["RequestDuplicationFilter_RequestDuplication"], ApiResponseCodeEnum.BusinessValidationFailed);
                     }
-                    IRCSystemInfo.RequestRecordList.Add(requestInfo);
                 }
             }
 
diff --git a/IRaCIS.Core.Application/BusinessFilter/_Config/_AppSettings.cs b/IRaCIS.Core.Application/BusinessFilter/_Config/_AppSettings.cs
index 757a1d7ae..1871801c2 100644
--- a/IRaCIS.Core.Application/BusinessFilter/_Config/_AppSettings.cs
+++ b/IRaCIS.Core.Application/BusinessFilter/_Config/_AppSettings.cs
@@ -146,6 +146,31 @@ public class RequestDuplicationOptions
 public static class IRCSystemInfo
 {
     public static List<RequestInfo> RequestRecordList { get; set; } = new List<RequestInfo>();
+
+    private static readonly object requestRecordLock = new object();
+
+    public static bool TryAddRequestRecord(RequestInfo requestInfo, int cacheTimeSeconds, int duplicationWindowMs)
+    {
+        lock (requestRecordLock)
+        {
+            var now = DateTime.Now;
+            RequestRecordList = RequestRecordList
+                .Where(x => x.RequestTime >= now.AddSeconds(-cacheTimeSeconds))
+                .ToList();
+
+            var isDuplicate = RequestRecordList.Any(x =>
+                x.RequestTime >= requestInfo.RequestTime.AddMilliseconds(-duplicationWindowMs) &&
+                x.RequestKey == requestInfo.RequestKey);
+
+            if (isDuplicate)
+            {
+                return false;
+            }
+
+            RequestRecordList.Add(requestInfo);
+            return true;
+        }
+    }
 }
 
 public class RequestInfo
@@ -236,4 +261,4 @@ public static class AppSettings
 
     }
 
-}
\ No newline at end of file
+}