Usermapper merge with duplicate UID

NAS1 and NAS2 both as primary Usermapper, both CIFS only.

Changing NAS2 to be secondary UM from NAS1.

Many of the same users have logged into both NAS1/NAS2 so same user names show up but with diffeent UID's

Planning on using UMDBmerger to merge both user/group UM files but how do I handle the ones with same username yet different UID?

For example: user "lmooso" below

$ grep lmosso 65_220_user

S-1-5-15-65d637a8-5b5506ca-462b3d83-57dc:*:39623:32768:user lmosso from domain _history_sid_range_:/home/S-1-5-15-65d637a8-5b5506ca-462b3d83-57dc:/sbin/sh

S-1-5-15-2d12c20a-4a50d687-3ff3757d-205b8:*:39622:32768:user lmosso from domain central:/home/S-1-5-15-2d12c20a-4a50d687-3ff3757d-205b8:/sbin/sh