csv_concat.py

import csv

files = ['file1.csv', 'file2.csv', 'file3.csv']

rows = []

for file in files:
    with open(file, 'r') as datafile:
        reader = csv.DictReader(datafile)
        for row in reader:
            row.append(row)

with open('outfile.csv', 'w') as outfile:
    writer = csv.DictWriter(outfile)
    writer.writeheader(rows[0].keys())
    for row in rows:
        writer.writerows(row)