The key question is whether you have an overloaded Multi Wire Branch Circuit (MWBC) or a big dangerous mess.
A MWBC uses two hot wires on different legs with a shared neutral. This gives you 20A x 2 safely. If they are on the same leg but different breakers then it is unsafe because you could have 40A (if balanced between the breakers) on the neutral without a breaker trip, so that is not a valid MWBC but can start out as a valid MWBC that gets reconfigured incorrectly.
And there is a third scary possibility. Somebody takes the two hots of the MWBC and combines them on one breaker. That isn't so unsafe but can lead to nuisance trips.
Take a look at the breakers for this circuit:
- Two breakers on separate legs (240V between them) - proper MWBC and you are having actual overload and need to move some appliances or receptacles to another circuit
- Two breakers on same leg (0V between them) - bad MWBC and you need to move one hot/breaker to the other leg. Since it is a MWBC must be breakers next to each other, double breaker or handle tied
- one breaker with two hot wires - split to a proper two breaker MWBC.