I was thinking maybe a couple dozen at most but usually about four or five. Maybe "private army" is stretching it a bit. Although I was thinking about adding the limitation that the more duplicates he creates, the more unpredictable they become or perhaps even become less intelligent or something. That way he could maybe create a hole bunch of clones but basically their only use would be to swarm a more powerful enemy.

I dunno. I'm still working it out.