连接集合和赋值

我有两个集合，我想根据键属性连接它们，并将一个集合的值分配给另一个集合。我是这样做的

var joinedData =   from collection_one in Office.Employees 
               join collection_two in NewOffice.Employees 
                  on collection_1.OfficeId equals collection_two.OfficeId
               select new { collection_one, collection_two};

// Declare a new Collection 
ICollection<Office.Employees> updatedCollection = New List<Office.Employees>();
// Assign New Collection_Two Values to Collection_One
foreach (var item in joinedData.ToList())
            {
                item.collection_one.Deleted = item.collection_two.Deleted;
                updatedCollection .Add(item.obp);
            }

没有产生正确的结果。My Join产生的记录比内部连接产生的记录要多。有人能发现问题吗?

    var updatedCollection =
        (from collection_one in Office.Employees 
         from collection_two in NewOffice.Employees.Where(x => x.OfficeId == collection_one.OfficeId).DefaultIfEmpty()
         where collection_two == null
         select new { 
             collection_one, 
             collection_two
         }).Select(x => {
            x.collection_one.Deleted = x.collection_two.Deleted;
            return x.obp;
         });