After thinking a bit, gnupg is doing wrong in asking to insert a card with a
particual serial number, it should actually look for which ccid card has the key
material with needed finger print and not look for which ccid card has a serial
needed serial number.
The serial key is creating problems with ccid backup tokens containing same
subkeys. Please fix this bug for gnupg be smart in handling multiple ccid tokens
with same subkeys.