Hi

Use this function to identify the duplicate.

Code:
Function ISDUPLICATE(ByVal ExeDate As Date, AccountName As String) As Boolean

    Dim k   As Variant, i As Long, d As Long
    
    AccountName = LCase(AccountName)
    d = CLng(ExeDate)
    With Worksheets("EXEC Plan")
        k = .Range("s6:t" & .Range("s" & .Rows.Count).End(3).row).Value2
        For i = 1 To UBound(k, 1)
            If k(i, 1) = d And LCase(k(i, 2)) = AccountName Then
                ISDUPLICATE = True
                Exit Function
            End If
        Next
    End With
    
End Function
and in your sub use it like

Code:
If ISDUPLICATE(CDate(Range("b6").Value), Range("c6")) Then Exit Sub