FWIW, there are only a few "real" +P loads- 9mm, .38 Special, .45 ACP, and ALL .38 Supers. Those are the rounds for which SAAMI established a +P load. They are loaded to about 17% higher pressures IIRC. While someone may CALL another cartridge a +P, there is no standard for other cartridges.
The +P+ is loaded hotter than a +P, but again, there is no standard for that load- so in theory, you would load that up as a 2 times pressure load.
SOME handguns- especially older ones, were not designed for the higher pressures. Unlikely to have an OMIGOD! kind of failure, but will cause accelerated wear on the gun.
What we have here is... failure- to communicate.