With the macrobreweries bought up by international conglomerates, have you noticed if the beer going into bottles or cans with different brandnames is the same?
Why would being owned by other corporations change the recipes of the domestic products? They are still brewed in the same US facilities - AB and MC breweries - for the domestic market, and, for the most part (the major exceptions being Bass and Beck's), the brands of the parent companies/partners - Molson, SAB, InBev - are still imported, brewed at their foreign breweries. That said, between the fact that both practice high gravity brewing and, probably, use post-fermentation hop extract, it would be easy to brew and ferment one basic wort, dilute at slightly different rates and/or add different hop extract and come out with several different "beers". Supposedly, Miller does that for a number of the brands they brew for Pabst, and also package the same liquid under several different brand names. But all that predated the foreign ownership.
I believe Bass used to do this decades ago, releasing the same beer under both the Bass and Worthington's brand names.