Turquoise Skull Mask

This image was sent to us by a reader in Canada, who tells us he obtained it ‘from a person who got it in 1967 at the World Fair in Montreal, Canada (Expo 67). He had bought it when they were taking the Mexico Pavillion apart...’. It measures 18 cms high. On the inner Jaw the numbers 2 0076-20 are hand written. It was sold on eBay in December 2009 for $2,650. Can anyone shed any light on this? It appears to be a well-made imitation of the famous Tezcatlipoca turquoise mask in the British Museum...