Only Apple will tell what's "real ProRes" – or problems with the footage down stream…
There used to be a paid transcoder for ProRes on the PC from Miraizon. But it was pulled, probably under pressure from Apple's lawyers. When I tried that at the time, some – but not all! – of my transcoded footage was not accepted in my editing system (Premiere by then). Some folks claimed it was based on the same function in Handbrake.
Now there is this one still:
http://www.acrovid.com/footagestudio.htmI have no idea if it's Apple acknowledged, but might be worth a try.
You are only on the safe side with a ProRes encoder qualified by Apple, this is a short list of (expensive) ones:
Assimilate Scratch
Telestream Episode Engine can encode ProRes on windows server 2008 and 2012
Clipster
Red has it in their RedCine-X now, but only for R3D sources.