I don't like using spot on treatments, as it interferes with the fleas breeding cycle. I would rather use the Frontline spray, which you have to get from the vet as it is still prescription only. Although it says it will last three months, I have used it every month if necessary, if the dogs have been somewhere where there are rabbits or hedgehogs.
Also you can use Frontline on puppies and kittens from 2 weeks old.
If you are not sure, why not contact the manufacturers and ask if they supply Vet-Medic? I would say 100% that it is the same product. They are a very big online company and also have stalls at Crufts and Discover Dogs and their staff are very helpful and knowledgeable.