Duplicate payroll check control numbers

We have encountered an issue where current payroll runs are creating duplicate check control numbers with converted payroll from several years ago. We are trying to determine 2 things.

First, how does JDE derive the check control number. We are set up to use next number with a check digit.

Second, we are assuming something was missed on the conversion of the old payroll. We are looking for suggestions on way to modify converted payroll records to prevent further duplication.