Shared hot bulb?

[TrainMaintainer]

Does a 2 (or more) cylinder hot-bulb diesel have to have a separate "bulb" for each cylinder, or can they share a preheater/vaporizer? Probably a bonehead question but I cannot see a reason why they can't share. Someone fancy explaining why?

 

[GreenTwin]

Seems like if the hot bulb were strategically located, then is should work.
Just a guess.

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