Some of the bigger companies offered protected territory to dealerships as as incentive to carry their brand. That meant there there couldn't be another dealer for that brand within a stated distance of each other. Companies could legally get around this by marketing multiple brands. A distributor like West Coast Cycle would sell one brand to dealer A and a different brand to dealer B, only a few block way. Often the differences between the two brands would be quite small. In some extreme cases, they could even be from the same manufacturer, with the only differences being the brand name, colours and graphics.

Edit: Another ploy was for the distributor to offer the dealer a house brand. The dealer might not be able to get his hands on brand "N" but the distributor could get the same bicycle from his manufacturer and have the dealer's name/brand put on it.