Sub SameMacroForTwoDropDownBoxes()

'The following line of code will tell you
'  in a message box which of the two
'  drop-down boxes initiated the macro
MsgBox Application.Caller

End Sub

Sub SameMacroForTwoDropDownBoxes()

'The following line of code will tell you
'  in a message box which of the two
'  drop-down boxes initiated the macro
Select Case Application.Caller
    Case "Drop Down 1"
        MsgBox "The first drop-down box has been changed."
    Case "Drop Down 2"
        MsgBox "The second drop-down box has been changed."
    Case Else
        MsgBox "No idea where this was coming from..."
End Select

End Sub