Technically this is a regurgitation (ejecting the contents of the esophagus, as opposed to stomach contents which would be vomiting)- and this sure sounds like you should only be feeding one item per meal. The snake was hesitant to take both- that should tell you something, eh?
Regurgitations can harm, even KILL. Snakes cannot really cough- & when they regurgitate something, they can easily aspirate some into their lungs. I'm surprised your snake actually ended up swallowing both- & you're lucky he's keeping both down.