How to draw textures without outline?

[Johanovski]

Hi there!

I'm working with my game using OpenGL ES and I want to draw textures without outline. I have a .png image wich have no outline, but when I draw an overlapping succession of this image it shows an outline from the upper image. This is, instead of drawing this:

( )

draws this:

((((((((((((((()

How can I prevent this effect? I'm using the renderAtPoint method.

Thanks in advance!