If I wanted to open a marijuana dispensary in a state where selling recreational marijuana is legal can I open up another one in another?

Yes, but the entire situation would be insanely difficult for you. On a federal level, marijuana is still illegal, and since banks are managed by the fed, they cannot accept your business. And so whatever money your business in the alternate state makes would be problematic to get back to you in your home state. Even transporting to the money home could be an issue, as if you cross through a state where pot is illegal, the police could stop and seize your vehicle along with the assets.

Welcome to the hell the marijuana industry faces.

You can open a dispensary in any place that'll give you a license to do so. It's not like just anyone can do this and the licenses to run such places are usually pretty tough to get.

Sure if you can meet the criteria for each state which is going to be very different for each state. Getting the license to open a dispensary in each state will be completely different and separate efforts (and expenses). The red tape to open a dispensary is substantial and presumably requires a good attorney but if you have the resources, go for it.

In another - where it is legal, if and when you are licensed to sell it, yes.