EGKK this is a kind of bull....
Sorry guys but this is not acceptable
This is where the scenery designer has put ramp starts on a gate that has three possible start positions. An aircraft would usually the centre position but they have L/R start positions so they can get two smaller A/C types on the gate. Because XP now spawns A/C at all 'Ramp Starts' they should only put one on the centre start position or both the left and right start, selecting the smaller aircraft size accordingly. This is in no way an error on Traffic Global, it just reads what an airport gives it. This can be changed by the user in WED, if you know or are interested in changing it.
I am presently working on a new Gateway version of Gatwick, which is nearing completion, you can find details of it at https://forums.x-plane.org/index.php?/forums/topic/168973-egkk-gatwick-re-work/
I hope this helps explain it a bit.