Here's a Columbian whitetail. My friend drew a tag a shot it last year in Oregon.

Hard to say what that antler came from without some form of genetic testing. I've seen a lot of blacktails sporting racks with whitetail charateristics but I've seldom seen a whitetail sporting a biforcated G2 like a blacktail/mulie, but your rack shows no definitive character one way or the other.