With a maximum slot of 32 there are enough slots to have fit each of the factions in twice and a bit more. If "double" factions are allowed than Stardock is going to have to find a good way of differenitating them.
Usually the way best way of doing this is just to had a bit on the end for example France, The Republic of France, The Kingdom of France. 3 Easily distinguishable faction. However considering that each nation already has a bit added on to them, ie Empire and kingodms. This becomes a pretty pointless method.
Perhaps the better way would be to eliminate doubles but allow the computer to randomly generate custome factions to fill the empty space. Have it choose a random name, pick a bonus (or Whatever?) and just go with that. I would really love to see computer opponents generate their own random factions it would save me time .
Brad has stated that he plans to have 32 factions in a "skirmish" as the maximum. However we are very early in the beta which is why we don't have that many slots.
Pigeonpigeon is right there are only going to be 12 factions: http://forums.elementalgame.com/329355/page/2