Mercenary reverted to a previous merc

I had an Eruptor merc, who I replaced with a better one. Several hours later the server glitched while I was in a Kirac map doing an Ultimatum and I was logged out. I logged in, and then had to log out and in again in order to rejoin the map. When I did, my current Eruptor was gone and the one I had replaced was back.