Hmmm...technically....yes. Keep in mind a couple of things though, since it sounds like you will be syncing to the same user account on your Mac and not different users with different data:
-You will need to update them constantly to reflect the same changes, otherwise you'll have one BB that is not complete.
-If you make a change on one of the BB's, and a different change on another before syncing them, and then attempt to sync both in either order, you will get conflicts which PocketMac will not understand, and may cause you to inadvertently lose data.
-As I've posted and warned numerous times to friends and on these boards, while you CAN sync a PDA/PIM type device to two computers, or two PDA's to one computer, this can and oftentimes does lead to data corruption. PIM makers have warned for years that it is not advisable to do anything other than sync one PDA to one data set on one computer, and nothing else. If you absolutely must sync two BB's to the same data set, then may I strongly suggest that you backup your data constantly! I have seen many saddened users that I support because they wiped out and trashed their Palm/PocketCE database because they decided to do something creative with it. By all means, back up data and you should be fine