I have never worked on a project where I have two project managers, but I am currently experiencing a similar situation where I have two managers in a lab and trust me it’s really helpful when you have two managers. Both of my managers are really friendly and amazing so if I have any question any time I can go ask either one of them. And I think the project become more fun and easier to manage when you have two managers and most importantly their is an additional opinion which might make the project more successful.