I just had in mind the probable place of collision if such collision is found. Let's say Key1 and Key2 are 2 keys leading to the same Address. So, it is more likely that public keys PubKey1 and PubKey2 are different. Then it is also more likely that SHA256 of PubKey1 and SHA256 of PubKey2 will be different. But the collision is in RIPEMD160 function transforming different SHA256(PubKey1) and SHA256(PubKey2) to the same hash, and then to the sme Address.
Indeed, for legacy addresses.
If the RIPEMD160 hash of the SHA256 hash of the private key was the same, the final address will be the same.
Since after hashing the Pub key using SHA256, the result will be hashed using RIPEMD160 and the next few steps will only be based from the second hash's result.
But that will only happen if there will be a RIPEMD160 collision.
And as you know it, its collision resistance is pretty "
strong" at 2
80.