Releasing the same app both for Quest and Rift - can a user pay just once and get both?

I'd like release an app both for PCVR and Quest where the PCVR version would be with higher quality graphics. However if a person purchases the PCVR version would they get the Quest version as well or vice versa? Or do they need to pay 2 times? Is there any way to make them pay just once?

Sorry if this question has been asked before, but I couldn't find any info on the topic.

Thank you!