Yea, pretty much, though for IPv6 if you just take a /64 as a single address and ignore anything else from that /64 as a duplicate it might be ok. Then again, so many of use have /48's from HE so...yea it needs to be thought out.
Well even now with IPv4 there are people with a shitload of IPs (for example botnet owners or ISPs), and that will only get worse. If bitcoin somehow relies on IPs being scarce, this is a pretty big (potential) hole in security.