You can have two main characters with a changing stats screen for each main character. See the Icarus Sun wip Icarus Sun (WIP - Update December 27, 2016) Changing stats when POV character changes .
I think it can be hard to pull off because you have to clearly let the reader know the character has changed. I think it’s better to have the main characters be defined, because with undefined MC’s, it can kind of be like the reader has to entirely create their own story instead of helping with someone else’s story.