I'm not sure if this is the same thing as 'batch numbers', but the number at the bottom of most perfume bottles are serial numbers. Each bottle should have a different number, no matter if you have 10 of the same thing. This serial number is also written on its original box, and it should always match with the number on the bottle.
However, the barcode on boxes will remain the same if the perfume(& size of it) are exactly the same.
In other words, let's say you had 10 boxes of Givenchy Play 50ml EDP. If you were to look at the barcode, they will all have the same number. But there is also a serial number on each and every box, and all these numbers should be different from each other. So when you open all 10 boxes, you should be able to find that same matching serial number on the bottle somewhere, usually somewhere on the bottom.
I ALWAYS check my serial number of my perfume. checkcosmetic.net is the place to go for that. After submitting the (usually, but not always) 4-digit serial number, it will tell you the month/year it was produced, and its expiry date.
Last edited by Robynlovesperfume (2012-02-20 14:32:57)