Because you are getting a new worksheet added each time your script runs, and the worksheet name is steadily counting up (sheet1, sheet2, ...), I think it is more likely that you are inadvertently adding one more sheet than you intended. Unfortunately, that would require you posting more of your code for us to confirm...

You could go about it by running through your script and then traversing again all of the worksheets in the workbook, deleting any that you don't want...but why not prevent the unnecessary one from being created in the first place?

So, more code please, and I'll take a look. Try to consolidate it as much as possible while still exhibiting the problem...then post the entire example script.