these 2 urls both show the changelog
https://webmin.com/archives/https://webmin.com/changelog/
the archive one come up first in the search engines for webmin changelog
Yes, this is all fine and expected.
maybe a 301 redirect instead of an alias/rewrite ?
changelog should not be archive 
No, that won’t really work, and I don’t think it’s a big deal to spend time on.