CLose call V belt ruined

So you removed a used belt then put it back. No doubt the tension changed and that is a factor. In many cases the orientation of the belt is a factor, meaning the outside should stay to the outside, always mark before removing. A correct section belt will not contact the bottom of the pulley \_/ . Drive should be the sides of the \_/.
So... installing a new belt... Alternator belt shouldn't be banjo string tight. Bearing in the alternator, water pump bearing/seal cant handle too much load. Just tight enough so pulleys wont slide under belt when turned by hand.
To be honest, I consider all new belts and hoses a required part of a new engine.