the function newOutline is working ok when no suffixes on the images are used. Having the two versions of an image file (triangle.png and firstname.lastname@example.org) the created shape used for the collider is twice the size it should be. It looks like it's taking the @2x image to create the outline and also duplicating it's size.
I saw something similar reported in other post, but in that case the outline kept the same size while changing the image (http://forums.coronalabs.com/topic/44103-fixed-how-can-i-use-graphicsnewoutline-with-2x-and-4x-image-substitution/).
I'm using build 2589, last one at this moment.
This is the code to reproduce this, and a picture attached to show how the colliders are seen in the two situations: