problem about Network Redirector Driver in win7

Hi everyone, I have a problem in Network Redirector Driver.It seems a bug of win7,isn’t it?
If I only have a ip like 100.0.2.*, I can map the disk under it as 100.0.2.*/vol0(z:) as well.But in win7,if I add another ip like 192.253.253.* in the advanced TCP/IP setting. I cannot map the 100.0.2.*'s disk any longer. Why does this happens in win7? The two ips work together very well in XP.