具有相同键的Hashtable项已经添加了ArgumentException

Question

我有这段代码：

    private User LoadData(uint userID)
    {

        User data = null;
        DataRow dRow;
        DataTable group = new DataTable();  

        //nonrelevant MySQL queries here.

        data = UserFactory.GenerateUser(dRow, group);
        while (loadedUserData.Contains(userID))
            loadedUserData.Remove(userID);
        if (!loadedUserData.ContainsKey(userID))
            loadedUserData.Add(userID, data);
        return data;
    }

我正在获取例如ArgumentException异常：

Item has been already added. Key in the dictionary: '370674'  Key added: '370674'

我似乎无法找到错误。我尝试了很多东西，但都没有。正如您所看到的那样，已经检查过，并且不应添加该条目。