Resizing a pasted graphic changes blending mode

[BoltBait]

I was working on a "photochop" yesterday where I was trying to add a soccer ball...

I pasted a ball on a new layer, sized it, and positioned it where I wanted.

Then, I pasted a second ball on that layer. While it was selected, I was able to move it so that it partially covered the first ball. It looked great, however it was just a little too big. So, I moved it back to the middle of the canvas and resized it. When I started moving it back over the other ball, I noticed that the transparent area around the ball was now replacing the pixels of the first ball. Resizing the pasted graphic caused the blending mode to change to "replace" instead of "normal blending".