A shop plugin, the CMS and an older static file may all publish sitemaps. Multiple files are not inherently a problem. The difficulty starts when they name different preferred addresses for the same content.
Record the sources and submissions
List the sitemaps referenced in robots.txt and submitted in Search Console. Add any known automatic exports. This inventory should show which generator owns each file.
Fictional example: the CMS lists /guides/delivery/, while an old plugin lists /blog/delivery/. Both display the same text, but only the first address should remain. Check redirects, canonical tags and internal links to establish the intended destination. The newest file is not automatically correct.
For each mismatch, record the chosen URL and the configuration responsible for it. Repeated identical entries are less urgent than contradictory hosts or paths that no longer exist.
Retire old outputs deliberately
Remove obsolete submissions and references once the current sitemap covers their intended content. Do not delete a child file still needed by a valid sitemap index.
Document which export owns each content type. During the next CMS or plugin change, this makes it easier to notice if a second generator has silently become active again.
Related check: Remove redirects from a sitemap.
If several exports have unclear responsibilities, the Technology and stack review can assess the underlying application structure.