For Dual gauge to work in Trainz you need essential two parallel tracks, or in reality, two parallel invisible lines made by Trainz on any model you set up to act as a track...
It do not matter how the track looks, Trainz as a program will always drive anything set up as a train along the X=0 in any model set up as kind track.
Hence, in order to make dual gauge work in the older days of Trainz, we made dual gauge as kind Bridge, which now a days is a no go as that kind seem to not be around anymore.
There is a way with the new attached track part of the kind track config, but essential it is still making two tracks into one track where neither of the tracks no about the other and trains can pass by each-other, through each-other and you cannot connect cars on one gauge to something on the other gauge on that type of track.
So, for you Zeldaboy14, it don't matter if you make a dual gauge track model in Blender - or anything else - you still need to tell Trainz to hook into that model so to speak two invisible tracks in order for it to work as a dual gauge track.
Linda