They definitely appear to be friends and not multis- In all of the games together they are chatting with each other the whole time.
As for a secret alliance? It's possible, but I don't think its proven in your
game. For most of the game they attacked each other more than you, and it looks like frickenrisky was trying to take you out when you were attacked a lot in Round 8. It can be tough to pull off in Fog of War, and riskybusiness was able to use that to his advantage.
If there are other games supporting a secret alliance I'd consider a block, but you are allowed to play with friends as long as you treat them like any other opponent. From what I've seen, they do just that (though it would be nice if they warned others that they know each other when the game begins).
