RE: Krash King part III - Beat this!
Third vote for aileron reversal. I've seen it happen to the best. They check that the ailerons wiggle (without checking direction) or get confused about the proper direction then your scenario unfolds pretty much every time. The roll evens looks faster because you are right on the ground.
I saw a guy maiden a giant scale P-51 with ailerons reversed. He's one of the better pilots in the club. Luckily he caught the error with his first movement and was able to climb VERY high while his spotter tried to fix things. It was a new computer radio so they were breaking out the manual all the while the pilot is going all over the place trying to maintain orientation and control. He was doing unintentional rolls, loops, and other indescribable maneuvers. They finally got the servo reversed and he landed to fly again.
FWIW - I always have my spotter confirm my control surface direction before a maiden flight or after major modifications to a plane. I check it myself silently then I move the surface and have him tell me which way it moved. So far so good.
The only other time I've seen that type of crash is with a high performance plane that didn't have enough airspeed to takeoff. I can't imagine a trainer plane would have a wicked tip stall. I especially can't imagine two different ones behaving the same way. All the trainers I've seen and flown will maintain a wings level attitude during a stall unless you have the CG way off.