jomo the opposite actually:
Set angle to No: the angle of motion will be independent to the display angle (self.angle) of the object (think of a ghost in a pacman, it does not rotate visually when the angle of motion changes, always the top of the head at the top, and the bottom at the bottom)
set angle to yes: the angle of motion will set the actual display angle (self.angle) to the angle of motion of the object (think of a pacman, it rotates with the direction it goes to to have his mouth going forward), the angle of motion is the one to overwrite the display angle.
@Aphrodite Thanks for your comments. And what you've described is the same with my original understanding - before I made the capx which attached with this post. I have no idea how to explain what I see.
And if you rotate the [Sprite2]'s angle to 0 in <Layout 1>, you'll see some more interesting things.
After that, set [Sprite2]' angle to 0.5, you might start to feel what i'm feeling now.