It's a system thing...don't sweat it. We see it all the time. There's no good explanation for it other than it's something that happens when you have weird shifts and codes all over the place.
If you think your pay is incorrect, you have can have your center put in a Payroll Inquiry and ask for your hours history, not your paycheck history. The hours history will show shift by shift, code by code, rate by rate exactly what you were paid. The paycheck history will show your total pay and any taxes and deductions for each paycheck.