This is what it takes to learn to fly a plane; if you want to learn to fly 2 planes in the flight school, you cannot do it in the regular 45 hours, it will take you over 60 hours if you are good, over 80 hours for most people.

I flew multiple aircraft in the same class and category while doing my PPL and had no problems. At this point there's old enough that's there's nearly as many differences between two C-172s as there are with a C-172 and a PA-28. Yes, it took me more than 40 hours but I blame that on scheduling, not the aircrafts.