I know Brian used the cream colored dupe on On Fire Live at the Bowl during Action This Day and Dragon Attack cos he had problems with his regular Red Special.
John Birch made a single (gold) duplicate copy as a back up for Brian in the late 1970's, but this was damaged one night when Brian got so annoyed at the sound he threw it off stage and there was no one the to catch it. This guitar can be seen in the We Will Rock You and Spread Your Wings videos and made an appearance at Milton Keynes.