every signature is doing you damage.

repeating an EC signature on the identical hash can quickly lead to dramatically lowering the cost of reversing the asymmetry of the secret to public key transform.

i dunno exactly what the signing protocol uses, but if the nonce used in it is weak, then the signature can be exploited later on to attack the account.

sadly this doesn't seem to have penetrated the thick skulls of devs who work with elliptic curve signatures sufficiently but signing on the same hash twice dramatically increases the chances of the secret being revealed.

just repeating:

never sign on the same hash twice.

this is also why bitcoin has HD keychains.

this is why nostr protocol needs to have a key succession algorithm, just as key changes are the norm with TLS/SSL connections.