You mean for this specific case? Yes, they’re two separate communities which is why it was disadvantageous to create a community on both kbin and Lemmy—if they made just one, that one community could share subscribers and comments and such from all Lemmy instances (that aren’t defederated) as well as kbin. They didn’t need to make separate accidentalrenaissance communities but they did.

I’m not a fan of the e-mail analogy overall, but here it works. It’s like they created a gmail account and an aol account, thinking only gmail accounts could email each other and only aol accounts could email each other. But really, if they made only a gmail account then both gmail and aol would be able to communicate easily.