That’s strange. They shouldn’t be able to tell two VMs are related. At best, that they’re coming from the same house hold. Did you manage to get your house IP banned?
Did you say anything on the 9 hour account that might have warranted a permaban? Anything that would have gotten a lot of reports?
They shouldn’t. They also check against user agents, browser extensions, and view window size, and probably a bunch of other identifing marks. Maybe it’s picking up on those?