Are they in the same phase? If you're getting 110v they pretty much have to be.
Several years ago my father in law tried wiring something for 220v and was only getting 110v.
I came over and discovered that he had used one of those tandem circuit breakers for both legs and was still in the same phase.
The only thing I could see is they placed the upper on one circuit and the lower on another. Maybe the were running two pieces of equipment at the same time that had a large draw on the breaker. Like an air compressor and a saw.