Interesting that Kew spells it both ways. As I understand it, the 'correct' spelling is how its first published, not whether its correctly spelt.I'll have to look up the part of Herr Röbbelen being either german or swiss (and if so, most likely from the german speaking part) - you might be right on that one, Happypaphy?
But on the spelling of the name of the orchid collector - and thus the correct spelling of the plant...c'mon, guys, give me a break! Don't tell me, that the multilingual Dr. Guido Braem, who lives and works in Germany (sic!), and who wouldn't jeopardize his academic credentials by not having checked the sources on the correct spelling of the name of either the plant or the man, got it wrong!
https://books.google.dk/books?id=aH...Q#v=onepage&q=carl röbbelen orchideen&f=false
And as for Kew - Kew Science, Plants of the world online, follows Cribb in placing the plant as a variety of philippinense, i.e. Paphiopedilum philippinense var. roebbelinii [the italics are mine]