Here are a few answers:

Walmart does get some manufactures to produce unique model numbers for their products that are exclusive to walmart. (sanyo TV's for example)....they will not have the same exact model at Best Buy.

The oil bar code is different because it was from a different production facility or coded differently to indicate refinery information.

The walmart brand oil can be manufactured by different companies (based on geographical location)....if you download the MSDS, you can find that it is actually quaker state or penzoil or whatever...based on location.

I worked in the lawn/garden department for 5 years while in high school/college. It was common for someone to buy the $99 push mower and mow over a tree stump and bend the crankshaft...then come in and get angry blaming the mower for the problems. Those type of people will blame the store and manufacturer when they clearly abuse the product.

I have heard someone say that the John Deere mowers at Lowes are not the same as the dealer...but you can get the same model number mower at both places....likely the same mower..just the consumer basic model. The dealer will also stock commercial grade models.

In the book The Walmart Effect there is an entire chapter about Snapper making cheap (compared to the rest of their line) mowers specific to Walmart and eventually they said F it to all the sales and said they didn't like how it was tarnishing their reputation.

I've bought from DT for what seems like 20 years and enjoyed great service.