Duplicate IP Addresses

MAC Addresses - locigal domain manager helps listen for vms= with same.

you can check with wireshark

enable port security on the switches

check for hardware malfunciton manufactrating.. or see if it was mac spoofing .

IP Addresses - ip address conflect. normally when there is a static ip set.

roughe dhcp server. causes connectivity issues.

check wether dynamically or statically assigned.