What does the number that is printed into a bottle of Johnnie Walker gold label mean?

My friend 'accidently' drank his sons bottle of johnnie walker gold label and then found out how much they cost and that his son was saving it for a special occion. We have been looking around to replace this bottle but are concerned that this bottle has an 02 imprinted into the gl at the bottom of the bottle. The son specifically wants an 02 bottle, is this a batch number or year number or something else? So far I have found 12s and 08s but no 02s! All help appreciated!