Yeah, that's what I thought would happen too, since I remember that happening in a previous campaign for Makedonia or KH, but nope, not this time. I'm telling you, Quintus, to your face, if you're listening, that I can somehow recruit BOTH the Camillan and the Polybian units at the same time as Epeiros. Both are still in the rosters for cities throughout Italy. This has been going on for a few years now (it is now 202 BC in my game, at about turn 282). So, either my campaign is a bizarre fluke, or you guys accidentally fudged something in the latest version of your export_descr_buildings file.
You might want to double check that then, huh?