The biggest group of Double Dippers are retired members of the U.S military. Reagan tried to limit double dipping, I don’t think he got anywhere or do military retires have to wait until 65 to start drawing military pension?
It’s complicated. My wife was a public employee in Ohio for quite a few years before they got pulled into the SocSec system in 1991. A public pension definitely reduces a person’s Soc Sec payout via the “windfall elimination provision” which was passed in 83.