Fixit-
That's basically correct. When you use the second ring as a compression ring it creates a high pressure area during the compression stroke, between the first and second ring. That pressure unloads the top ring (which seals from pressure from the top) and power drops. Combined with the losses from the very high tension
oil ring that is required due to the lack of a scraper and what you have are rings that are most commonly found in street engines, where the power loss is not noticed.