Im not saying anything but...
There are atleast 5 
there were supposedly 200. as far as we know, all of them except this one have been destroyed
i believe the system says "sony playstation" because it was probably branded with that name after Nintendo cut ties with Sony. the playstation was going to be an snes compatible cartridge/cd console. the main disagreement between Sony and Nintendo was who retained control of the licensing. Nintendo gave Sony full development and control of the SNES-CD disc format, thus giving sony a lot of control over software licensing. when it came down to it, Nintendo didn't like the deal, which is why they hooked up with Phillips and announced they would be working with Phillips to produce an SNES disc based addon. they announced this some time after Sony had already announced the playstation the same day. Nintendo's agreement with Phillips eventually spawned the Phillips CDi, and Sony moved on to work alone on a new console for the next console generation.
this is probably just a prototype to try to figure out what they could do with a new console. controller ports, different buttons, the volume slider seen in this prototype, the shape of the system, the disc drive, etc. they wouldn't have known what to do about the controller just yet, so they used a sony-branded SNES controller as a filler.
just a guess.
here's a good video that goes over the entire situation in detail.