apps/cs/src/pages/organization/ui/additional-user-dialog.tsx

@@ -100,7 +100,9 @@ function AdditionalUserDialog({
               취소
             </Button>
           </DialogClose>
-          <Button onClick={handleAddUsers}>추가</Button>
+          <DialogClose asChild>
+            <Button onClick={handleAddUsers}>추가</Button>
+          </DialogClose>
         </DialogFooter>
       </DialogContent>
     </Dialog>

apps/cs/src/pages/organization/ui/user-organization-section.tsx

@@ -98,7 +98,13 @@ function UserOrganizationSection({ ognzSn }: UserOrganizationSectionProps) {
       jbgdSeCd: "",
       sortSeq: 0,
     }));
-    setUserList([...newUserList, ...userList]);
+    const filteredUserList = userList.filter(
+      (existingUser) =>
+        !newUserList.some(
+          (newUser) => newUser.userUnqId === existingUser.userUnqId,
+        ),
+    );
+    setUserList([...newUserList, ...filteredUserList]);
   };
 
   const handleToggleSelectUser = useCallback((user: User) => {