Did you change your IP at any time?  If so, your ARP cache could have a record of the 
old address for a little bit, and the new one would have the same MAC, and that would 
be your duplicate.  Thats all I could think of as far as the duplicate MACs go.

Jon

On Thu, 18 Mar 2004 21:43:33 +0100
Sigfred H�versen <[EMAIL PROTECTED]> wrote:

> On Thursday 18 March 2004 21.28, Kirk Ismay wrote:
> > Slightly off topic, but has anyone ever seen 2 separate systems with
> > the same MAC address?  I thought this was a "never supposed to
> > happen" kind of thing as MAC's are supposed to be globally unique.
> > However, I've had this happen twice now with clients on my ADSL
> > network (I use an OpenBSD/PF box as a router/dhcp server).
> >
> > In the first case, it was an onboard AOpen NIC on the motherboard,
> > this time it seems to be an SIS nic. (Judging by the vendor prefix).
> >
> > NICs are usually in Windoze systems, so I'm not sure if I can use
> > software to set the MAC. And if I could, is there a 'private' range
> > for MACs that could be used if I did set it to something else? That
> > way I don't accidentally give them another mac that might be
> > duplicated.
> 
> In some BIOSes there are options for setting the MAC address  for 
> onboard LAN. If you have access to the PC's, that is.
> 
> /Sigfred
> 

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