When building modules in koji, there should be one module with some NSR tops, but when building module in Copr, we should be able to have multiple modules with same NSR - one in each project.

I suggest that we add something like namespace column to module_builds table, so we could check duplicity for owner/project/nsr.

Or easier solution, since module duplicity is checked on application level, not via database constraint - add config option to not check duplicity at all. Builder side should handle it somehow. Of course this option would be by default false.