The hpi:hpl plugin generates hpl files for a jenkins home folder.
When you execute hpi:run it uses PluginWorkspaceMapImpl which generates .jpl files for snapshots found on the user home folder.

This can cause hard to track conflicts as you will end up with an .hpl and .jpl file and the .jpl, which can come from any place on the home user folder, will have preference when starting jenkin.

For reference:
.jpl creation - https://github.com/jenkinsci/maven-hpi-plugin/blob/aaf092abf2853410c2101c3e521b515831484dea/src/main/java/org/jenkinsci/maven/plugins/hpi/RunMojo.java#L410
.hpl creation - https://github.com/jenkinsci/maven-hpi-plugin/blob/aaf092abf2853410c2101c3e521b515831484dea/src/main/java/org/jenkinsci/maven/plugins/hpi/HplMojo.java#L166