Are you asking if its possible to take two module roles and to make them one module role? Or if its possible to assign to module roles to the same role? If its the latter, then yes you can assign two module roles to the same role.
Edit: I don’t think that’s possible. If you have to merge two module roles then you would have to pick one module role and change all of the access rights of the second module role to be for the first module role. I’m assuming you want to do this because your domain model is very big and you want to prevent issues from manually redoing all of the access rights?
Say you have modulerole1 and modulerole2. And you want to merge modulerole2 into modulerole 1.
An easy way would be to remove modulerole2 and then to fix all the errors. You would have to open the access rights of each entity and in the “Rule applies to the following module roles” just select modulerole1.
If you don’t want to delete a module role, you could just open up every entity and add the modulerole1 to all of modulerole2 access rights.