I was trying to locate the circuit breaker for an outlet in my garage and found a truly baffling setup. Two breakers control the same outlet (both plugs). After some head scratching, I opened the breaker box and found (see pic) breaker 4 (20 amp) wired to the outlet as expected but breaker 34 (30 amp) wired to breaker 4. Why would this be done? It was obviously intentional and possibly setup for a freezer. Is this safe and in anyway an accepted practice?

Thanks everyone for the help! I know enough to keep from getting electrocuted and this just didn't meet the logic test. I'll be checking the wiring and hopefully this is the only work they attempted.