Find and select all non unique nodes in a Maya scene

find_non_unique.py

allDagNodes = cmds.ls(dag=True, sn=True)

allDagNodesLong = cmds.ls(dag=True, sn=False)

nonUnique = [ node for node in allDagNodes if '|' in node ]

values=[]

for n in nonUnique:
    for ln in allDagNodesLong:
        if n in ln:
            values.append(ln)
            
print values
cmds.select(values)