Can recently vaccinated and dewormed puppy travel with non-vaccinated and dewormed littermate?

We are picking up our puppy, who was just dewormed and vaccinated yesterday. We may be taking a second puppy as well, that was unclaimed from the same litter. The second puppy has not been vaccinated or dewormed yet. We need to travel about 6 hours with them. Is our puppy safeguarded from any possible worms for a few days now that he has been dewormed? I would like to put them together for the trip, for comfort. But if the second puppy could possibly pass worms back to our puppy, then I will keep them separated.