Excellent. You just need to find the other 1 billion of them.
what does this have to do with a billion more keys, if the question was, if hashes160 have the same prefix - can they be in the same key range or not.
and by the way, Bram also collects data on address prefixes at the beginning and end of the search range at the beginning of his full brute force.
Well, that wasn't the question. Maybe you should read it again, it's exactly opposite to what you understood.
Collecting prefixes is just meant to prove the range was scanned, since it's impossible to cheat and produce prefixes to your liking. That is the whole point of using statistics - checking if everything is alright, not defying the rules of nature and its randomness fluctuations. Besides, he's not even collecting prefixes of the target hash, but leading zero bits, which definitely do not help with anything whatsoever (except as proof of work).
I have an insane amount of 44 bits prefixes for 68, but decided to not share them this time to not fuel the prefix fire. On 67 people still managed to read something into the proofs I published…