The two numbers are both octane ratings associated with the Motor Octane Number (MON) of the fuel. The first number indicates the octane rating of the fuel tested to "aviation lean" standards, which is similar to the anti-knock index or "pump rating" given to the petrol (gasoline) which you can buy for your car.The second number indicates the octane rating of the fuel tested to the "aviation rich" standard, which tries to simulate a supercharged condition with a rich mixture, elevated temperatures, and a high manifold pressure.
Cheers
Steve