It's a Topic that made it to the release notes for v2.3.6 in September of '23.
which links to a how-to Topic:
USING a version of HPM that can't find the app list will cause duplicate apps to be installed. There's also a Topic about duplicate HPM apps in Apps Code:
If you didn't USE HPM during the mismatch, then updating HPM is all that's needed.
I think a lot of people got caught because breaking changes on Hubitat are very rare. That encourages people to upgrade without reading the release notes with an eye for upgrade order.
