I can see everyone else is trying to explain it but feel like it could be made clearer.
During two train operation one train faces each way. On departing the station, each train enters the turntable. each train departs the track on the loop-back that returns it to the turntable. The turntable then drops the train onto the final leg back to the station. Each train returns to the station facing exactly the same direction it left.
Train 1: Forward>Backward>Forward
Train 2: B>F>B
During one train operation only one train is on the track. In order to offer the alternating experience, the train must return to the station facing the opposite way to how it departed. In this course, it leaves the station, enters the turntable, departs onto the loop-back circuit into the turntable again, however in this situation the turntable drops the train back onto the loop-back circuit for a second time, before dropping onto the final leg. As it completed an extra loop back, the train returns to the station the opposite way.
In one train operation, due to the extra leg completed, the ride time is longer and you get to see the loop-back section from both directions.
Train first dispatch: F>B>F>B
Train second dispatch: B>F>B>F
I feel like if you experienced one train operation first, I can understand why the two train operation experience feels 'less' because the ride time is shorter. For everyone who rode under two-train ops, getting to ride the one-train circuit feels like a 'bonus'.