The description of iPod 2 iPod - Play With New Friends
If you have more than one iPod at home and you want to transfer songs between them, you will not be able to do it by using iTunes, you'll need a third-party program and we recommend you iPod2iPod.
iPod2iPod is extremely easy to use, you only have to connect two iPods to your PC and run the program. You'll see that the interface is divided into two parts: The left side will show the content of your iPod and the right one will feature the content of the iPod where you want to copy the content from the other one.
When you want to copy it you only have to choose the songs you want to copy and click the arrow between the two parts to add the content, then, add them to a new playlist and save changes. That's all.
If there are more than one iPod at home and you want to share your songs or you want to share your songs with a friend, iPod2iPod is the perfect tool.