I donít know jack squat about canned tomatoes, but I did work in the Walmart/Samís Club sales office of one of the worldís largest agri/food companies for 10 years. It is mainly an ingredient/food service company, but dabbled in supplying retail to keep the plants running at full capacity. Only a handful of retail brands, and most of those were regional. Mostly supplied store brands, so while I canít comment on canned tomatoes specifically I do have a lot of experience with producing for private labels. Products ranged from fresh meat to vegetable oils to flour to salad dressings to frozen chicken wings, and beyond.
Even though it may seem like it from the below, Iím no fan of Walmart. Just trying to explain how things work from a first-hand perspective. Iím pretty sure similar principles apply to most major retailers.
Saying Walmart is ďnotoriousĒ for contracting out production of private label items is a little harsh. Retailers arenít in the production business. All of them (with perhaps a few specific exceptions) work with outside manufacturers specific to the need to produce private label products.
Iím not quite so certain you can identify a ďname brandĒ under a private label. Many are supplied by companies like the one I worked for which have little retail presence but are skilled in producing the product. In the same vein, many ďname brandsĒ donít make their product either; they contract it out and slap their label on it just like the retailers.
The way it works for supplying either a private label or a national brand is they give you the specifications for the final product. If you can make the product to the customerís satisfaction at a price point they can live with, you get the bid.
Walmart doesnít change suppliers willy-nilly. Itís usually on an annual basis--depending on product-- unless a supplier was unable to fulfill their commitment (small/new companies are notorious for submitting a low bid to Walmart thinking theyíll cash in on big business, only to find out they canít handle the volume). They also typically want at least 3 different suppliers for their house brands. That way, if one suffers a catastrophic failure, they are not out of product across the country, and theyíll lean on the other suppliers to fill the void. So, for many food products people in different parts of the country will get product from different suppliers.
While a different supplier will certainly deliver a different product, Walmart can also change the specs on their house brands which can affect the end product from all manufacturers.
Tying it all back to tomato cans: I suspect there are a lot more numbers on the can cited above than were given. Typically on food products the numbers describe (for those with Little Orphan Annieís decoder ring): The plant where it was produced, the lot number (identifies all product made in the same batch), and the pack date. Might also contain other relevant information to the specific product.
Given the same code across brands in the posts above about canned tomatoes, Iím guessing itís for the production facility. But that doesnít necessarily mean itís the same product. As I suggested above, different customers have different requirements, and the supplier makes to the customerís specs. As an example, I worked with a plant that made hamburger patties for Walmart, Samís, Sonic, Burger King and a few others. The patties for each customer had a different formula, but had the same USDA plant ID stamp.