I think Doppelganger would win this pretty easily despite Sabretooth's healing factor..
What makes you say easily?
Doppelganger is basically Spiderman but bloodlusted. So Doppelganger has better reflexes, strength, speed and abilities. He would be able to over power Sabretooth if it came to h2h and if not, he could spray from with razor sharp web. The only thing Sabretooth has on Doppelganger is he smart but I don't think he's smart enough to get himself a victory here..