How about this expression?
(From p in BuildDt.Select() where( From q in BuildDt.Select() where q("Id").Equals(p("Id")) Select q).ToArray.Count>1 Select p).ToArray.CopyToDataTable()
You can try to get the Duplicate Record from ID column
Check out the XAML file
LinqGetData.xaml (10.5 KB)
Output

Regards
Gokul