Private Sub Worksheet_Change(ByVal Target As Range)
Dim t
If Target.Column > 1 Or Target.Row = 1 Then Exit Sub
Application.EnableEvents = False
If Target(1) = "" Then
Target(1, 2) = ""
Else
t = Now
If Target(1) = Target(0, 1) And _
t < Application.Max(Columns(2)) + 3 / 86400 _
Then Target.EntireRow.Delete Else Target(1, 2) = t
End If
Application.EnableEvents = True
End Sub