Hi McBainMcCartin
We have encountered a similar situation for some other company files, generally its caused under circumstances by the user entering a slightly different number. clicking off the value and then entering the correct one - however it does happen in other situations. Whenever you are processing payroll, we would recommend ensuring that you have the correct values when doing the Review Pay Run Summary step.
In terms of correcting that payroll transaction we would recommend deleting that and reentry as per Help Article: Edit or delete a pay run