I'm sorry, but it just confuses me, because both works and I always think that there's only one correct answer. In my mind it's either can or could. - That's where your first language can be of some help: do not hesitate to use could each time there is бы in the Russian version. By the same token, can will be closer to the Russian sentence without бы. In a word, the difference between can and could in your example will be basically the same as between можем and смогли бы.
So, I shouldn't stick with the same tense either?