In Allowance conditions, I have seen some horses pop up and win at big prices when running for a tag when they could run under a N2X or otherwise. I have to look back but I remember some shrewd trainers on the Illinois circuit 10-15~ years ago where they would claim cheap, win a N1x, run for the 40k N2x for the tag, WIN, and then run protected under the N2x next time out.
Of course there's no way to tell Formulator to show me all starts where they ran for a tag when didn't need to, but if you pay attention, you might be able to find something.
Or it could be trainer or agent screwing up the entry!
(I've had this happen as an owner)