.is the existence of partially perforate stamps mentioned in any other catalogues?
Of course !
but only if they were issued so. perf horiz, perf vert etc.
or if a known and listed error "variety"
Stamps perforated privately.
I'd suggest stamps as yours would attract "printers waste" or "damaged"
I would have it under my "oddments" or "curiosities"
Stuff like this abounds in Cent Lith material, including dodgy postmarks.