If you are seeing the same payslip twice or more than once under Self Service, this is caused by payroll periods being set up incorrectly.
When you have more than one payroll period for the same month linked to the same Payroll, this will cause payslips to appear more than once in Self Service.
To resolve this:
Click Setup, then Settings.
Click Module Settings, then Payroll Settings.
Click Payroll Period.
Search for the duplicated periods and click one of them.
You cannot delete it, but you can edit its dates to set it up as an upcoming period that hasn't been created yet.
Once you've set up the new period, click Save.