Within a single job, we need to source branches from multiple repositories that we do not have control over. Currently, if the same branch name occurs in different repositories, only the first is built and subsequent identical branches are dropped.

I suggest that the remote name (if configured) be used to disambiguate the branches, so that they can all be built.

eg.
Remote name: linux
Branch: master

Remote Name: linux-next
Branch: master11

These would be resolved as linux/master and linux-next/master.