Sounds like you're running aero, then? Let me tell you this: Pumps can fail. And in aero, pump failure is a much bigger deal than ebb/flow other styles. If anything, you should at least get 2 pumps to have one as a backup.
Are your veg systems both aero? If so, you might get away with using a single pump. The size of your pump depends on how many sprayers you're running. Since you didn't supple that information, it's hard to give you an answer. Some people say you need at least 25gph/sprayer. It's hard to say, because flowrate is not the same as pressure. For a reference, I run a 400gph pump in my cloner, which has about 14 sprayers