IP's overlapping on cisco?

[lynxus]

Hi guys,
I have a question.

I have my cisco configured and can ping google. However i want another interface in the same IP range?

I have:
interface Tunnel199
no ip address
ipv6 address 2001:470:1F08:795::2/64
tunnel source 212.125.xx.xx
tunnel destination 216.66.80.26
tunnel mode ipv6ip
end

With HE's end being 2001:470:1F08:795::2/64

What IP do i use for another interface or even another host on teh network?

I try:
ROUTER(config-if)#ipv6 address 2001:470:1f08:795::/64  eui-64   
%FastEthernet0/0: Error: 2001:470:1F08:795::/64 is overlapping with 2001:470:1F08:795::/64 on Tunnel199

And was assuming it would fill the rest in with the MAC address but it doesnt.
Am i completely misunderstanding something here?

-L

[broquea]

Do not use the point-to-point on other interfaces. Use one of the two routed allocations:

Routed /48:       2001:470:9233::/48
Routed /64:    2001:470:1f09:795::/64

Also HE's side will never be what we've designated as the "Client side" as we aren't the client, we're the server.