That's not correct...
ITunes has been changed to accept multiple iPods after apple realised that some familes have lots of iPods and one computer. My PC has iTunes on it (once) and i run 5 iPods from that.
You just have to make sure it's not set to auto update all the iPods or you may lose songs or get ones on there you didn't want.
Search on the 'support' section of the Apple site for multiple iPods on one PC - it tells you what to do
Gareth