I believe the difference in spelling is attributable solely to people's difficulty in using the correct spelling, which is "Witcomb." You'll probably be able to search out more info using the correct spelling.
http://www.classiclightweights.co.uk...s/witcomb.html
Like Masi, Witcomb also set up a US operation on behalf of a US investor using the Witcomb name, which at one time boasted Richard Sachs and Peter Weigle as builders.