It will vary based on your sourcetype, field extractions, and definition of "multiple login done by more than one pc".
To search for users signing onto a single server multiple times, you might try something like:
"login successful" | stats count by uid, server | where count > 1
To search for one server that was accessed my multiple accounts:
"login successful" | stats count by server, uid | stats count by server | where count > 1
