[topherjaynes]

If you read the citation they're following the original source, which isn't the common usage either, but at least it doesn't seem as glaring now.

http://www.jstor.org/discover/10.2307/2683689?uid=2&uid=4&si...

[pash]

The various spellings arise because the television host's real name was Monte Halparin, and he used the stage name "Monty Hall" [0].

0. http://en.m.wikipedia.org/wiki/Monty_Hall