That's similar to what Ethereum's proof-of-stake does. Any staker can submit the two inconsistent transactions as proof of malfeasance by another staker. When t

That's similar to what Ethereum's proof-of-stake does. Any staker can submit the two inconsistent transactions as proof of malfeasance by another staker. When that happens, the misbehaving staker is automatically "slashed," losing a portion of their stake.