Barcode App Help

[Richard Monheit]

Hi There,

I'm not sure if this is the right area to be posting but I'll give it
a try anyway.

I'm getting a company to build an app for me and one of the key
aspects is that a user scans a barcode from a product and gets
rewarded through credits (which can later be redeemed for prizes). The
problem I have is that the barcodes aren't unique, so there is nothing
stopping somebody from scanning the same barcode multiple times to get
the credit. I want the user's scanning behaviour ideally mirror their
behaviour, and essentially reward them for effort. How can I set up a
program that rewards the user for scanning a non unique code but also
doesn't allow for people to abuse the system?

Any thoughts you have would be much appreciated.

Thanks very much

Richard