Actually, you can keep the two versions from the same Stationery. It's a bit tricky, but if it is the only way... I've tested it already, and with success. From NeoGaf:
So, the Delete Stationery function actually has a practical use it besides helping people that don't care about catching them all. If you set things up right, it will let you keep/use all versions of any stationery that have regional differences. All you have to do is have a version of each stationery in your mailbox. (It's easier if you favorite each version for quick access.)
For example, if you want to use the FallBlox stationery, but you live in the US and have already had the Crashmo version overwrite it, all you have to do is delete the Crashmo stationery from your stationery list (note: NOT the note you received the stationery from) and then look at your note with the FallBlox...View full quote