Professor Triplex

[Scrooge MacDuck]

Reading Gottfredson's Blaggard Castle for the first time (…I know), I have made a bizarre discovery: the very first strip says, emphasis mine: “In a dark house on the egde of town, two evil professors plan to lay a trap for Mickey!”. The art indeed shows only Professors Ecks and Doublex, a duo that would often be reused sans Triplex in future appearances of the Professors. Yet in the very next strip, with no forewarning, the letter is signed by all three Professors. Then for many, many strips, Ecks and Doublex are again acting alone, until Triplex sort of materializes out of nowhere halfway through with an aggrandizing caption introducing him as their "leader". 

So…what happened there? Did Gottfredson remember Professor Triplex at the last minute, or make a last-minute decision to add a Prof and make his duo a trio? And does this have anything to do with how Triplex would later tend to be "squeezed out" in stories by other authors, only leaving Ecks and Doublex?

[Dr Ivo G Bombastus]

The characters are clearly based on the Mad Doctor from the cartoon of the same name, where he's referred to as Dr. XXX. Triplex was doubtless intended to be the main villain from the beginning; Ecks and Doublex exist to provide a pun.

Most stories most likely only use two of the doctors for the simple reason that two characters who babble at each other are good for exposition, but three is a crowd. The average comic plot isn't complicated enough to justify having so many characters, and the original Blaggard Castle's decision to save the Man Behind the Man for a dramatic reveal can't be reused.