There are two actual octaves, 87 and 91 (excluding racing fuels, etc). The pumps with multiple blends actually blend the fuel in the pumps. The octane levels are routinely checked by state regulators. You can test the ‘heat’ in the octaves by putting a little of each on the back of your hand, you can actually feel the difference in octane.
Years ago I had a hot-rodded Beetle. I was out in the country for a gig, and needed gas. Stopped at a station that had “purple” racing gas, so I tried it. Wow!