It’suncommon and possibly worrisome if two ECDSA signatures produce identical u1 and u2 values during verification even though their r values differ since u1 = z / s mod n and u2 = r / s mod n in ECDSA, both u1 and u2 must match for the s values and the ratios z/s and r/s to produce the same result in both signatures you mentioned that the r values differ, which suggests that either the signatures were generated incorrectly or with forced equivalence, or the same s was used (which is uncommon and dangerous if it comes from reused nonces k)  this behaviour is abnormal for standard ECDSA signing and may indicate improper implementation or reused randomness it may be intentional if you are intentionally simulating or creating signatures (for example, by granting access to only the public key)however, if this happened during actual signing it is worthwhile to audit your signing procedure for security vulnerabilities