101 Brand Names, 1 Manufacturer (2007)

Especially supermarket generic brands, but also other products.

The article itself says "ingredients, designs and quality may differ substantially among the labels made under the same umbrella. "But often the main difference is marketing -- and price -- and that can be hard to sustain once products are perceived as commodities. "

Also:

"Some consumer-product companies have been forced to make both generic and branded products to please retailers. "If a major manufacturer is unwilling to produce private-label products, there's a possibility the retailer won't sell their branded products" (another thing retailers do is force companies to give free samples or special discounts if they want to keep selling to a major chain).