For each Totem, you need a keeper. So that's two individuals right there, meaning you'll need two units, one for each individual. Two totems, two keepers, four units and so on. You'll be rackin' up to some high point games the more you build like this. In a 2000 point game, taking 3-5 hours, I might run with one keeper and totem, or just a keeper, and have plenty to work with. I would be curious to see a Dwarven force constructed with 2 totems and keepers. Hmmm.....
To answer your question I think there is no restriction to the number of totems, you just need to follow the restrictions for keepers and individuals/units.