Quote - I just ran both PP2010 & PP2012 together on my computer and they are distinctly separate although I had to open the PP2010 Library from the Windows menu at the taskbar.  Content loaded into each without any problems.  Installation for each app generates separate folders with separate dedicated files.  I am assuming that installation was allowed to place those files in their default folders.

Yes they were put into their separate default folders.

I tried reinstalling PP2010 yet again, and then opening it first. The first time round it opened as 2010 and then the library came up. I tried inserting content into the document window and it inserted it into 2010. I thought maybe it was finally working. Howver, I opened up PP2012 afterwards and it wasn't opening with the PP2012 library but the 2010 one. So when I tried to insert content into 2012 it went into the 2010 program.

When I closed down PP2010 and opened it up again, only the library controls came up. The actual PP2010 document window technically was there, but whenever I clicked on the icon I could never access it. I can't get into the 2010 window now for some reason, but the library always launches.

So the two Posers do seem to be somehow connected on my computer. Whichever one I launch first becomes the primary Poser and the second one opened is just another copy of that and not its own separate and independent program.