Finding If The Copied Data Is A Duplicate?

I use this code below to copy information from various sheets on to one sheet,

PHP Code: 

Private Sub CommandButton1_Click()
Application.ScreenUpdating = False
Dim copySheet As Worksheet
Dim pasteSheet As Worksheet
Dim xrow As Integer, xcol As Integer

[code]....

i use a command button to run the macro, but i would like something added that if someone else pressed the button and ran it again that it would check to see if it had duplicated the previous line and if it did it would delete it leaving just the one record for that week.