Well when I feed multiples I usually just wait until she re-aligns her jaw and is looking around for more. I think there was a time or two she killed it (I feed live) and didn't eat right away. I put the mouse in with her and looked back a few hours later and it was gone. I don't feed multiples every week though given the fact shes only about 2.5 ft long. I'll usually feed 2 about once a month with her. I wouldn't think there would really be a problem with the setup given the fact hes still eating, just not as much. He may just be slowing down his appetite, or maybe try switching back to rats again to see if you'll get a better response with them?