Double or redundant devices

Hello,

I have Windows Vista, service pack 2. My device manager shows two 6T04 adapters and Teredo Tunneling Pseudo Interfaces. One of each works properly, the second one does not. Am I supposed to have two of each of these devices? Or can I disable/uninstall the ones that aren't working properly? Will it make a difference? Or should I leave them as they are.:confused:

Thank you.