....and can I use both with the same address??

Okay, I have my S10/x64 system running, on-board NIC seemed to be a bit
juddery, so I disabled it and stuck in a card, it works.

Now, I have a WAP & router and an ADLS Modem & Router, linked together,
with various systems hooked into them, and I was wondering if I could
simply connect the other NIC to the other router, set the IP address on
both NICs to be the same, and have it all just work?

IIRC, SPARC systems do this by default (or perhaps they have the same
MAC address).

ASCII art follows, IP addresses are for illustration only):

+--------+ +--------+
| ADSL & | Current | WAP & |
| Router |------------| Router |
+--------+ Link +--------+
(10.0.0.1) (10.0.0.2)
| |
| |
| |
Current | |
Link | |
| |
| |
(10.0.0.3) |
+--------+ Proposed |
| S10 |----------------+
| | Link (10.0.0.3)
+--------+

Is this sensible? Okay, I don't mean *sensible*, what I mean is will it
work?
The S10 box runs Squid, so I was thinking that this sort of setup would
reduce the traffic on the ADLS side from the wireless connected systems.

Cheers,
Gary B-) (Waiting for the howls of derision ...)