Quoted from jrpinball:
Absolutely! Double the rubbers on any rounded top 2" flipper. It's because of the long ago change from a 1 1/8" ball, to a 1 1/16th" ball. The flipper didn't change, so this is a factory recommended remedy. It was fixed when the flat top flipper was introduced.
Always wondered why most 2in flippers back in the day had two sets of rings,
I always prefer to make the top flipper ring be a red ring for a cooler look.