Can someone explain how the difficulty modes work in Kingdom Hearts: Birth by Sleep?

Ok, so I finished the game with Ventus first in Standard Mode. Then, I decided I can do a little better and decided to finish Terra and Aqua in Proud Mode. Now, if I redo Ventus in Proud Mode will the Secret Ending be unlocked? That means I did Terra, Aqua and Ventus in Proud Mode but finished Ventus in Standard Mode once.