After a battle, I had the option of two units to take into my retinue, in the first slot, I had a level 3 Minotaur King, in the second, a level 3 regular minotaur. In my retinue, I had a daemon, and an empty slot. I moved the minotaur king into the empty slot, then moved the regular minotaur in place of the daemon. However, after clicking on the daemon, a high elf guy with a spear and no name appeared in the place where the minotaur king had been originally. I clicked on that guy, and moved him in place of the regular minotaur, and he turned into a copy of the minotaur king, giving me two identical minotaur kings in my retinue. Sorry I lack screenshots or more data, but I was a bit confused as to what was happening and didn't think of taking any.