As mentioned over Matrix, Tap adds the field MPR-Package: ${pkgbase} to the deb's control file. This should let Una recognize that there's previously installed MPR packages, in turn Una should also mark installed packages as MPR packages.
[x] Mark the packages so other helpers can recognize them
[x] Read marked packages from APT so Una can recognize packages installed by other helpers
I've added the MPR-Package field, as well as an MPR-Version field with the version of the package in the MPR cache (not pkgver) at the time of installation.
As mentioned over Matrix, Tap adds the field
MPR-Package: ${pkgbase}
to the deb's control file. This should let Una recognize that there's previously installed MPR packages, in turn Una should also mark installed packages as MPR packages.