There's 2^160 different public keys, the chance of hitting one of this accidentally is so vanishingly small that it doesn't even warrant thinking about it. The improbability of this event is literally the basis of all cryptology; big keyspaces are difficult to bruteforce without unlimited resources and unlimited energy.
If you analyse it as probability it makes a lot more sense than intuitively thinking about it. A login & a password combination can also be seen as a unique string combination and so is 2FA i.e. a 3 string combination. Not really multiple levels of security mathematically.
