Ok , first, never use anything you find in the international models forum for any US model. They are very, very different devices. If you made an image from mmcblk0p3 as stated in that thread, you actually made a copy of sbl2 I'm pretty sure.
Also, the imei, (the important thing here) is not actually stored on the efs partition as it is in some other devices.
Run the command I posted before for the best solution. If NV corruption is ever detected, it should auto restore from this backup during boot up.
And again, stay away from the international forums. Most of the info there will not apply to our devices here and many, many people have bricked due to that mistake.
And delete the backup you made. If you were to try and restore it to your device after updating it at some point, it would most likely cause a brick.