It's not possible having any difference in the path taken by the baggage loader ( or any other vehicle ) from Boarding to Deboarding, assuming the airplane is the same and the gate is the same and the plane was parked in the exact same position.
The only possible difference, that *might* affect some vehicles crashing into each other ( but NOT the path taken ), is a randomized time delay between the start of each one, which is the only thing that might cause a session of vehicle not crashing into each other, and another one with a different result.
The plane parked in two different position between boarding and deboarding is the only thing that might cause a different path taken at different times.
As explained so many times here, GSX vehicles are not able to detect each other while they are moving, because even if we could do that without killing fps ( doing that would require every vehicle checking all the others, at each frame, which will spam Simconnect with too many commands, so it's not doable ), it would create a whole new class of problems, like deadlocks on the limited space in the apron, which would be far worse than the otherwise completely harmless and momentary "crash" of vehicles into each other, because deadlocked vehicles will likely freeze if deciding to yield to each other. So, you must accept vehicles sometimes clashing between themselves as the lesser of the two evils.
Also, please clarify what do you mean with 737-800. FSX comes with a default 737-800, and there are many 3rd party, each one might or might not have a proper GSX configuration for it. And, please indicate if you created one and/or changed the one that comes with GSX for that plane, assuming it did had one.
