There is no way to know by just looking. Some red dogs carry the gene but you wouldn't know with out knowing the family tree. Both dogs would need the gene for the possibility of getting tri pups.
As was said before the best way to produce the dogs you want is to be well informed and dog yur homework. If you don't know what you are getting out of a litter, then you dont really have a shot bettering the breed. Only people trying to better the breed should be attempting to breed dogs.
"Cull hard on people. The people even more important then the dogs, great people made these dogs." -The Chosen Few -