Scanning Code of Practice - each flavour is free, right?

So my mom and I had an issue at Walmart today. The Rice Thins had a sign saying $1.88 and they scanned at $2.67. So I got a free bag no problem, once they checked the price. My mom had 2 bags of different flavours (so different UPCs) and customer service said only one was free. We said no, SCOP says each different UPC is a separate error. So in the end the supervisor said "just give it to her" but I don't think they really believed us.

So I was googling SCOP because I want to make sure we were right, but I can't find anything saying that separate flavours would both be free anywhere! I found this:

"Where the same error recurs in scanning multiple units of a given product during a given transaction, the retailer will correct the scanning error in respect of each unit of the given product purchased, but is obliged to apply the policy set out in 1.1 (a) and (b) in respect of only one of the units" (source)

which seems to say similar item = only one free but doesn't really specify whether they mean identical items or just similar items.

So, we were wrong? Or does anyone know of an official site that does say different UPCs mean every one is free?

Thanks for any help :)