I hope you're right, John, but I don't think you are :-)
My research shows the Sonitus plugins being re-released by Cakewalk in 2004. (there's a lot of really old stuff in Sonar).
I doubt plugins would have been 64-bit back then.
As for the xxx-64 plugins, they're (apparently) 32-bit plugins with 64-bit internal processing, which explains the 64.
Please, someone, prove me wrong.