The boxed set comes with both... if you bought via download, you need to buy again to get the different version
ok thanks, that sucks... Can I get it at upgrade price, or do I have to pay full price again?
The boxed packaging is not sold by Adobe direct. If you want to explore that type of purchase which offers the perk of a Windows and a Mac installation disc, you need to purchase from an authorized reseller who is not going to offer you "upgraded pricing". The seller would be its own entity with its own pricing and own return/refund policy. Sometimes the authorized reseller price may be less than the Adobe"upgraded pricing".
Did you purchase your Premiere Elements 13 Mac from Adobe direct and are within 30 days of purchase? If so, you can contact Adobe Chat Orders to ask for return/refund. And, then you can explore the authorized resellers for pricing and availability of the box packaging. Maybe check out the pricing all around before making any final decisions.
Please review and consider.