I didn't get a barcode thinge, but a tag with a sort of cable tie that had a label on it of the form Pnnnn (where nnnn is a four digit number)
Dealer said to hang onto it if you ever need a replacement key/chip.
I got one of these 'tags' with my first i10.......... but not with my 2nd one. A quick email to my (very helpful/friendly) dealer asking for the number and I got it soon after. Just make a note of it somewhere safe.
In all likelyhood, there is only 1 tag that comes with the car. The dealer will either make a note of the number on the computer system, and then give you the tag for your own records, or just remove the tag completely.
When I picked up my car, the tag was actually attached to the keyring.
It is worth phoning the dealer and asking for your cars 4 digit number, so you can keep your own record. You dont actually need the tag itself. You never know, the dealer may manage to lose it somehow, and in that case it will be a very expensive job, as I'm sure many dealers will deny any responsibility.