Furthermore, "highly unlikely" is an understatement. Using SHA256 there are 2^256 hashes. That's 11579208923731619542357098500868790785326998466564056403945758

Furthermore, "highly unlikely" is an understatement. Using SHA256 there are 2^256 hashes. That's 115792089237316195423570985008687907853269984665640564039457584007913129639936. Probability of collision (two different inputs generating the same hash) is infinitesimal.