There's a closed pull request on the void-packages repository

xbps-src: depuplicate output of setup_pkg_depends
https://github.com/void-linux/void-packages/pull/21493

Description:
Issue #21044 raised problem of setup_pkg_depends returning duplicate results after depends of subpackages were included. Specifically, problem was performance and triggering failures of xbps-fbulk.

I was unable to reproduce fbulk's misbehavior, as show_pkg_build_depends deduplicates its output. Yet I don't see reason for listing duplicates here.

Please merge if you find it good.