Electro-Harmonix also produced Big Muffs for other companies in rebranded enclosures. These were not alternate circuits, but the same pedals EH was manufacturing at the time, simply screen printed for specific companies or music stores.
One of the most well-known examples is the Guild Foxey Lady, which included both Triangle and Ram’s Head era circuits.
Based on the units I have traced, these are identical to their Electro-Harmonix counterparts.
Other OEM versions worth noting include the Wabash, Lyle, and Marveltone. These are
rare and difficult to find.