I have two 6509s with Sup2/MSFC2s. I have HSRP configured between the two MSFCs. I periodically receive the message shown below. I have several Vlan interfaces, and it will occur on different Vlans. My HSRP address is .1, the two switches are .2 and .3. I am running Native IOS 12.2(18)SXD4.
%STANDBY-3-DUPADDR: Duplicate address 172.31.20.2 on Vlan20, sourced by 0000.0c07.ac01
Has anyone seen this before?