as the owner of a dog aggressive dog I think its highly irresponsible and selfish to let them roam and attack other dogs, I would be mortified if my dog did it once never mind twice.

I would definetly report it to the dog warden ( dont think the police will do anything) - I would also be inclined to give the man a vets bill for the bites. (regardless of whether it actually really needs vet treatment) If he is hit in the pocket perhaps he may take it seriously.

Also if they know where he lives I would write a letter stating the above and that perhaps in future he should either muzzle or keep his dogs on a long line.

It isnt easy having a dog aggressive dog, but thats because you should be extra careful when walking and make sure that you dont run into these kinds of confrontation. attacking once could be put down to an accident but twice is just downright selfish and irresponsible