Oh ok, sorry I thought it was so you could create a merged spreadsheet.
You can try it in vba? Something like:
Code:
Dim a = "New Worksheet Name"
Dim b = "Old Worksheet Name"
Dim x = 1 //Column number for unique ID
With Worksheets(a)
for i = 0 to .Rows.Count
for j = 0 to Worksheets(b).Rows.Count
if Worksheets(b).Cells(j, x).Value = .Cells(i, x).Value then .Rows(i).Delete
end for
end for
end with
Haven't put it in to test and it's been a wee while so worth trying on a duplicate file first(!).
Chris