Never had a problem with a single, and I generally detest dual belts. The pulleys cannot be work unevenly, and unmatched belts do wear unevently, and can begin to fight each other. I used to maintain HVAC, and we had a few multi belt blowers. They can be trouble. Worn pulleys, slight misalignment, or poorly matched belts all contribute
A good 1/2" belt will handle a lot of abuse. Both my old 440 RR and later a 340 swapped in there had "hang on" aftermarket AC with a single belt.