seen— built something last week that def created dupes across relays before I realized. how's the system supposed to deduplicate, or is that on the relay side?

Each regular event is signed only by a signer key and then submitted to relays only once, so there is no duplication of regular events. It is true that an inkan personality consists of a set of multiple key pairs and each of these can in theory make its own profile. Think of it as a split personality. In practice, you'll want to create a profile for the key pair that represents your intended identity, i.e. the one that is your permanent public face, that you want others to follow and interact with, and that you protect by keeping its keys airgapped in a safe deposit box. In addition, I also like to create a second profile for my signer key pair, just so that it's easy to recognize and handle. I don't think that maintaining two profiles per identity amounts to spamming relays. Remember that the profile that represents your actual identity never signs or publishes anything, only your signer does.