The proper name would probably be a - 'split base' double tackle .... @ (4:1) .
its ability to act as a traveller is very limited .... cant move this traveller to windward or 'drop' the traveller without having the boom also rise (but not as much as without such arrangement and only using the 'normal' in-line blocked mainsheet system). You're going to need a very strong VANG to make this common old-fashioned system 'work well'.
Definitely not something that would replace a traveler... Oldsailer, if that's tempting you as a way to get around your mainsheet/bimini conflict I don't think you could stand behind the wheel without entangling yourself in that arrangement....
OldSailer, I have a friend with a set up something like that, but only has (2) blocks, one on a short traveler(about24" long)bent rod in the shape of a 'U' at the stern that the block/car(?) moves on, and the other bloch is on the boom. Is that something C&C used? If it is, I'm glad mine has a car!