In #1331, conflicts were added to module-build-macros as a means to force the rpms from buildrequired modules to take precedence over rpms of the same name from base modules.
However, if the same NVR is present in both the base module and a build requirement then mbs will still add the conflict, which results in a build failure.
@jkaluza would you say this is a fair description of the issue?
Commit 88636138 fixes this issue
Commit ed86a2ca fixes this issue
This issue has been migrated to Fedora Forge: https://forge.fedoraproject.org/koji/mbs/issues/1660
Please continue any further discussion there.