Older Player...

[Keydah]

I'm really not sure, to be honest. Obviously, the "must buy on each platform" only applies because of Sony needing to get a cut of sales as part of how they operate, so you can't buy a PC version and then use it on PS3/4 as then Sony gets no money. The same rule doesn't apply to Mac, because as far as I know Apple doesn't need a cut of the sales.

I swear they've answered this at some point in one of the live letters, though...But I can't remember what exactly they said. >.<

Either way, like Sakuraluna said, if you do need to purchase it twice, don't buy the CE twice. The CE applies to the account, not the platform, so it's a wasted $20.