[TR] Regarding the no. stamped on the brass tag on the ZS carbs

[sujit roy]

 I have two tags with me. One has the no. 2477 3509R. The other has 3146
3509L. Firstly, how many tags should a pair of carbs. have?
Also, can someone please tell me about the numbers?  If there is supposed to
be only one tag, one came off my Stag the other might have come from a TR7,
but I'm not sure which one.

Thanks, Sujit