example_getCode.py

import csv
files = [
    "a.csv",
    "b.csv",
    "c.csv",
    "d.csv",
    "e.csv"
]

BASE_PATH = "base_path/tobedecided"

codes = []
for file in files:
    filePath = '%s%s' % (BASE_PATH, file)
    with open(filePath, 'r') as f:
        reader = csv.reader(f)
        header = next(reader)

        for row in reader:
            codes.append(row[1])

d = {}
for code in codes:
    if d.get(code):
        d[code]+=1
    else:
        d[code]=1

for k,v in d.iteritems():
    if (v>1):
        print k