And if IIRC a dual can have a different ratio than a single pulley. So that can really change performance - not always for the good.
I had one local shop (whom I'd never recommend assuming he was still in business) do a swap to a pulley for a large belt to keep the ratio (maybe?) but make it less likely to fly off. That's the sort of quick and dirty things that can be done to fix problems. Of course doesn't always make it right or good.
