lucre double-blinding? (Re: Crypto-making vs Crypto-breaking)

[Nomen Nescio]

A Back asks:
> It's been a while since I looked at the Lucre white paper but
> extrapolating from the Chaum context doesn't double blinding mean the
> payer and payee have to be simultaneously online with the bank?

No, this is something else.  It just means that two random numbers rather
than one are used to blind the data when it is sent to the bank to be
signed (oops, "transformed").  Doing this makes it impossible for the bank
to recognize deposited coins even if it misbehaves.  Earlier proposals
that used a single random blinding factor were shown to be inadequate.