I have seen how the AI puts 12 units in the same tile, but each unit in a different army, instead of combining them in the same stack.  No need to say that is silly and pissing.

http://imageshack.us/photo/my-images/528/12units.jpg/

Although it generally does the stacks, sometimes it feels like can be improved. Please try to give a fix to the AI to improve in combining armies.

 Edit: This game is in normal/normal. I wanted to design better Jugs for the AI for future games (now, facing yithril will really be scaring hehe). The AI is a Quendar customized (was double power than Magnar, untill I attacked).