Deselect True Post-Requisites when searching for Required for Upgrade fixes.
In the Critical Search Criteria is a checkbox
True Post-Requisites for (Select) Previously Applied Fixes.
This is checked by default.
The nice thing about this is that it checks to see if the fixes that you have previously applied have newer post-requisites that should be applied. This is great as you will never miss knowing about a new fix for something you have already applied.
Unfortunately, data conversion scripts are written with the records and fields all being exactly as they were at a specific point in time. You do not want to apply newer fixes (post-requisites or others) except for newer Required for Upgrade (RfU) fixes.