Alt. Esri Find Identical

select_identical.py

import arcpy

def select_identical(lyr,fld):
    d = {}
    f_lyr = arcpy.MakeFeatureLayer_management(lyr)
    with arcpy.da.SearchCursor(f_lyr,['OID@',fld]) as cursor:
        for row in cursor:
            fld_value = row[1]
            oid = row[0]
            if fld_value not in d:
                d[fld_value] = {'OIDs':[oid],
                                'multiple':False
                                }
            elif fld_value in d:
                d[fld_value]['OIDs'].append(oid)
                d[fld_value]['multiple'] = True

    selection_oids = []
    for k, v in d.iteritems():
        if v['multiple'] == True:
            selection_oids.extend(v['OIDs'])
    sql_set = '(' + ','.join(map(str, selection_oids)) + ')'
    where_clause = 'OBJECTID in {}'.format(sql_set)
    if len(selection_oids) > 0:
        arcpy.SelectLayerByAttribute_management(lyr,"NEW_SELECTION",where_clause)
    else:
        arcpy.AddMessage('No duplicates to select')
        
if __name__ == '__main__':
    lyr = arcpy.GetParameter(0)
    fld = arcpy.GetParameterAsText(1)
    use_shape = arcpy.GetParameterAsText(2)
    if use_shape == 'true':
        fld = 'SHAPE@XY'
    select_identical(lyr,fld)