When I upload an image of say size 940x300 it is being resized by wordpress with the extension 940-300. This is completely unnecessary and also creates a worse image because the full size image IS already that size and optimized.
I was pretty sure that WP did not create this redundancy, yet I am witnessing it in the most recent theme I am using.
I am also using wp_get_attachment_image_src as it is the command which is searching for the image and returning the one with the extension.