Broder is not a company or producer. It's a general term applied to all counterfeit, illegal, and unlicensed cards. The term comes from Ed Broder, a photographer who produced his own cards in the 1960s and 1970s.
The backs of the Series I cards actually state "# of 20, Series I". Problem with these illegal cards is there are no official, legitimate checklists for them. Unless a checklist card was made with the sets.
Someday my cards may double in value and then be worth half of what I paid for them.