Do not do this, Walmart movies come in specially marked, if they do not have the sticker on them it will ring up the higher price.
ive been doing it for years..yes most will be different upcs, but at the time of sale they will up same sale price...now what you have to watch out for is whether its a combo pack with digital copy, just bluray, or bluray/dvd pack
just be aware that some walmarts try to take the movies off the shelf before sale too