I am currently trying to allow users to usedid:3 without using the 3id-connect modals, however while integrating I found that every time the same seed was provided, a new DID was created.
To investigate, I set up a demo project which only generates a DID from seed, and confirmed the behaviour.
Code providing seed to ThreeIdProvider: https://github.com/carlfairclough/ceramic-3id-demo/blob/758b67eb0ce121c1534e9bb9def11d0626493f21/src/utils/connect.ts#L20C1-L24C6
Demo: https://ceramic-demo-eosin.vercel.app/