Hey gents -- I'm not sure how well that would work. Each bulb would suck air from the other side, seems to me. I guess if you squeeze long enough on one bulb, you will collapse the other bulb and then might draw fuel up from the tank(?) Dunno. I'm also not sure how well the split feed would work when the motors are running and drawing fuel.
In any case, it's usually a good idea to have separate fuel sources for each motor (eg., main motor and a get-me-home trolling motor). If a tank or fuel supply fails, you don't lose use of both motors. Or put another way, you can use either individual motor if you have one working fuel supply (assuming the hookups are the same, fuel ratios, etc.)