There was a time (fad?) when this was done to off-road engines and you would use a piece of fuel tubing to connect the two nozzles.
I can't recall the exact reasoning behind this, but I think that it had something to do with vacuum or pressure pulses - or something to that effect.
To use this engine, you can either connect them using the aforementioned piece of fuel tubing or seal the nozzles or another method to simply plug the holes.