The "Go Green" version is probably just a hand-picked card which happens to work at a lower voltage than most.
No, if you go to newegg you can see the cards are different in at least some caps, a heatsink, and the power connector.
I'm sure they do cherry pick the GPU so they can undervolt it some but the card has visible differences.
If you want to compare the pics it is the 3rd pic in each gallery for
I had problems making the second URL collapse. Had to remove "&Description=POWERCOLOR Go! Green AX5750 1GBD5-NS3DH Radeon HD 5750 1GB 128-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card
" from the URL as SPCRs BB didn't like the length or one of the characters in the full URL.
The pics aren't from the same angle but if you compare them I think you will notice more than one change on the right hand side of the card between the 3rd and 4th heatpipe.
The 4th picture on each gallery shows the other side where if you zoom in it is clear a different PCB is used on each card.
One is version 1.0 and the other is version 1.1 so it is possible that you may be able to get the 1.1 revision in the non green card or it is possible that the 1.0 revision is for the non green and the 1.1 is the green. Just depends on if your interpretation or mine is closer to the truth.
I don't know for a fact that the green card is a different layout of the most current non green. I do know that there are two different layouts and that at least leaves the possibility that one is specifically for the green product.