To the best of my knowledge, straight species viburnums don't need a pollinator. They will fruit more heavily with one, but it isn't necessary.

My understanding is the same as Terry's. But to have a heavier fruit definitely plant different species that flower at the same time. That way they will cross pollinate. From what I understand, a named cultivar is of the same genetic material so cannot cross pollinate each other. For example, blue muffin arrowwood (no matter where you get them) are from the same parentage and so will be of no good to each other. On the other hand, if you have a blue muffin and another of a different name or a straight species, they should be able to cross-pollinate each other as long as they flower at the same time.

I am no expert though. I would try to find someone or even search the old threads to find some info from Kevin z5(?) or Viburnum Valley. They are both what I would call experts on viburnums and have posted some great info on this forum on this topic over the years. If you have no luck doing that, I would hop on over to the shrubs forum.