I think you need to detect which side is being collided with for it to work right.
Maybe you could do something like this?
Sprite on collided with tiledbg
Sprite.y<tiledbg.top
Or
Sprite.y>tiledbg.bottom
bounce vert
Sprite.x<tiledbg.left
Or
Sprite.x>tiledbg.right
bounce horz
A more robust way could be to compare angles like
Angle(tiledbg.x,tiledbg.y,Sprite.x,Sprite.y) is within 45 degrees or 0
bounce horz
Anyway just some ideas