Wireshark-users: [Wireshark-users] Duplicate use of IP detected

From: Soju Master <sojumaster@xxxxxxxxx>
Date: Sat, 5 Jun 2010 10:13:40 -0400
I was running a scan and started to notice these summaries:
 
AsustekC_ad:e3:e7     Dell_80:75:35     ARP     10.0.1.35 is at 00:1a:92:ad:e3:e7 (duplicate use of 10.0.1.180 detected!)
Dell_9d:29:af     Dell_80:72:79      ARP      10.0.1.230 is at 00:23:ae:9d:29:af (duplicate use of 10.0.1.181 detected!)
 
I have done the obligatory research to see if there is a duplicate IP on the network and could not find any.
 
Anyone know what this message means?
 
Thanks