I think of it as a variant. It's the same program but with 64 bit precision.
Just like we have the section "Compiled versions for older, 32-bit processors" for download in miller's site. As far as externals go, those have the same problem and one would need to get pd 32 bits just to run old external libraries not available for the newer Pd. One example is the [hid] external that we just now made available (finally).
And in the end if we have downloads for Pd 0.52-0 in 64 bit precision, then it'd be Pd 0.52-0 just like the one with Pd with 32 bit precision...
So yeah, I guess we need to make it available for download for 32 bits precision as well, just like we should keep the ones for 32 bit processors and even for PPC (although no new versions will be made available I guess as miller's machine broke, so probably not).
So, just make a section "Compiled with double (64-bit) precision" and another as "Compiled with single (32-bit) precision"
As for how the app comes out. I remember that when it was something new, the ones compiled for 64-bit processors had a different name. Now it's the other way around. For example, the mac one comes as "i386" at the end of the app name!
We can just have something like that and start by making a distinction, with something like Pd-0.52-0-double, and some time in the future (up to 3 versions later the most, I guess) it'll be the "regular" one and the others can be called Pd-0.55-0-single.
cheers