I was given a used iPod nano 3rd generation I already have a iPod 3rd my computer recognizes my iPod when I plug it in but will not recognize the other one with same cord any ideas?

Is your iPod recognized by your PC or do you just have this problem with iTunes? Try connecting your iPod with another usb cable, change usb ports, connect it to another pc. On the link section, I leave a link to more tricks for having your iPod detected.

Good luck!