It is meant to be a fully compatible replacement with additional features, hence ships the same command. Check it via:
dpkg -l | grep openresolv
That /etc/resolvconf.conf exists and has an effect is a prove of openresolv being installed, as resolvconf doesn't ship or use such a configuration file. openresolv does a lot of magic, basically it loops through all local resolvers it knows, including Unbound and (standalone) dnsmasq whenever via DHCP or RA any previously stored info changes (or even if it did not change, I can't find the related topic currently), and updates/creates a configuration for them with the provided DNS server address and then restarts their service. This can close a DNS loop:
Pi-hole => (as you configured) Unbound => (as configured by openresolv) Pi-hole
EDIT: Here the other issue: Unbound frequent restarts - #97 by MichaIng
Sorry for the messy post, I edited it a few times when understanding more and more how openresolv creates the problem with frequently restarted Unbound 
. And now I see that it was even you @jpgpi250 involved in this topic already. I hope you now understand why I recommended to purge openresolv all together 
.