[gervase]

I think this might be a side effect of the Keybase UI, not the service itself. If you interact with the APIs directly and look at the JSON, you can see that at a high level the proofs are a dict, with each service as the key, and the value is an array aggregating several proofs. You could therefore potentially have several Twitter proofs associated with different accounts ("nametags") that could then be presented all together if someone wanted to tie all those accounts to your identity.

I only skimmed TFA, so I'm not sure what the process would be like for actually validating those proofs, but the backend datastore seems like it wouldn't have a problem, at least.

[eridius]

The new Proof Integration Guide explicitly says that a Keybase account can only be linked to a single identity on your identity service (but that you can link multiple keybase accounts to that same identity if you want to).