This achievement is STORY BASED and must be completed to progress.
Unlike the previous battle with double Minotaurs you do not have the luxury of an Aniform Control Device. You do however have a lot of weapons, ammo, molotovs, and explosive grenades. When you make it to the center of the room you have a few seconds before the Minators attack - pick up a SAW and / or Shotgun and make sure your molotovs and explosive grenades are fully stocked. The trick to this battle is to run / walk backwards around the giant stone fountain in the middle of the stage. Use your molotovs and explosive grenades and keep shooting the Minotaurs.
The only time I had trouble with this one was on Easy the first time. After I got the hang of it I was able to defeat both of them with ease on Normal and Hard. After you defeat both of the Minotaurs the achievement unlocks and the door in the back of the room opens and Black Order troops come out.