Yes, you can. But amule have nothing to do with that. You should configure proper routing path and/or link aggregation to use more that one internet connection no matter what program we're talking about.
This is complicated issue, so make sure you undestand what is "routing", "link aggregation", "how ip network work". No, this is not a joke.
You talking about "primary route". This generally mean, that there's some another route, now unused, that will come into service when "primary" fails. Large organizations using such setup for redundency/fault tolerance. Do you have 1 link for traffic and 2 links for redundancy ?!