Can you please suggest a fix for this error?
This error code means that packets with same source MAC address coming from two different interface. That means you may have a netwrok loop causing this. You need to go to devices connected to interfaces Gi5/9 and Gi5/23 and check where this MAC is learnt on those. And trace it further same way checking the STP details.
By this you will find a loop to fix it. Most common cause is High CPU on one f the switches in the way or uni-directional link causing STP problems.
Also do a show cdp neighbor and see if the switch sees itself on those 2 ports , if so then those 2 ports are somehow physically tied together and must be fixed , spanning tree won't always fix this situation though it should.
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