He discusses fake name use in this post to Cypherpunks List in 1993. He also mentions "Digicash" in the same thread.
http://borg.uu3.net/ldetweil/medusa/originals/unpleasant
"In my limited experience creating Internet pseudonyms, I've been quite distracted by the continual need to avoid leaving pointers to my True Name lying around -- excess mail to/from my True Name, shared files, common peculiarities (eg misspellings in written text), traceable logins, etc. The penet.fi site explicitly maintains a list of pointers to the original address. All kinds of security controls -- crypto, access, information, inference -- have to be continually on my mind when using pseudonymous accounts. The hazards are everywhere. With our current tools it's practically impossible to maintain an active pseudonym for a long period of time against a sufficiently determined opponent, and quite a hassle to maintain even a modicum of decent security. Pointers to info and/or tools to enable the establishment and maintenance of a net.nym, beyond the standard cypherpunks PGP/remailer fare with which I'm now familiar, greatly appreciated. Especially nice would be a list of commercial net providers that allow pseudonymous accounts.""