I know that at least at one time, Sams and
Walmart were able to persuade certain manufactorers of software and electronics to issue different bar code numbers (SKU or item number or whatever they're called) on the items for them, because Sams and Walmart sold so many.
This enabled them to avoid the whole price match thing because they could say "Bar Code doesn't match so it's not the same thing."
There are many reasons I don't shop at Walmart, and this is just one of them. (Of course I realize that I am lucky enough to have options and a lot of other people don't.)