If Sheet Exists Stop Macro from Creating a Copy

Hi everyone. I would really appreciate assistance on this.

I have the following code that is part of a larger code:

 
    Worksheets("Sheet1").Copy After:=Sheets(1)
    Worksheets("Sheet1 (2)").Name = "SO"
    Worksheets("Sheet1").Visible = True
    Worksheets("SO").Select

This copies Sheet1 to the end and renames the copy to "SO".

Is there a way to modify the code so that if someone tries to run the macro again and SO already exists, it just stops and doesn't create another copy of Sheet1?