When I was swimming, I was counting lengths (in a 20m pool) but noticed there had been more lengths registered on the watch than actually completed. I have the distance set on it and goes up in multiples of 20 like it should. I started recording intervals after 2 lengths to check, and some are showing as 80m rather than 40. Overall in an hours swim, I counted 1720m but watch says 2280m. I thought I was very consistent but the watch says otherwise (because of the distance issue)