Origin of Sandwich? Seemingly it was from the Earl of Sandwich, in Kent UK.
He was a Montagu- not a Montagu of Montagu and Capulets or Romeo and Juliet or even West Side Story -but a Brit aristocrat. He was a Belted Earl-- and you can have a happy guess at who did the belting. Obviously a man of True Grit!
There will always be different pronunciation of words, only the locals know the correct way it was meant to be. I live in Melbourne, not Mell Bourne as most of our US friends would say it.