] As I understand it, Mallorca is more the local way of spelling it - Majorca is the English speaking way derived from Castillian Spanish. Presumably when the British were out there in force, they used the 'high' Spanish names.

Florence is called Firenze in Italian. and Naples is Napoli. I think it has a lot to do with foreigners not knowing how to pronounce something, so they make sonething up that is similar in sound.