A sailfin molly is one with a particular dorsal fin shape, not a particular color pattern. A dalmatian molly is one with a particular color pattern, not a particular dorsal fin shape. The two characteristics are completely unrelated. It is possible to have both in the same fish but not at all necessary. I have had many dalmatians over the years that had normal fins and I presently have a very nice pair of sailfins that are a plain silver color, not dalmatians. I like both kinds but do no insist on them being present in the same fish. If you have both in the same fish, they may well be gorgeous fish.