When installing the DSF Proteus libraries, I noticed the following:
multisamples are installed for both Rapture Pro and Dimension Pro
Program files are not.
 
Fortunately, it seems that the .prog files inserted into my Rapture Pro directory are actually Dim Pro program files, so all I needed to do was copy back from one directory to another.  Still, it's a little irritating to have to do that.

To be honest, if you have RPro, then you don't need DPro, unless for some reason you prefer the UI of DPro.
However, I agree, it is odd. You should report this to DSF.

AFAIK, all the new DPro and Rapture installers work this way if RPro is installed. I believe the change was made so that RPro would stay current. Either copy the programs into the DPro and Rapture program folders as required like the OP did or use directory junctions to point the legacy synth program folders to the new locations.