Keep first and drop the next duplicate rows

I want to keep the first row from the set of duplicates. I am also trying to append the current input file. My doubt is if both deleting the duplication and appending the same file, will it be possible? If so then the code below referring the Pandas doc isnt working.

Input:

,id_merged,time_1,time_2,gps_1or3,gps_2or4
0,00022d9064bc,1073260801,1073260803,819251,440006 #duplicate_keep
1,00022d9064bc,1073260801,1073260803,819251,440006 #duplicate_remove
2,00022d9064bc,1073260801,1073260803,819251,440006 #duplicate_remove
3,00022d9064bc,1073260801,1073260803,819251,440006 #duplicate_remove
4,00022d9064bc,1073260803,1073260810,819213,439954
5,00904b4557d3,1073260803,1073261920,817526,439458
6,00022de73863,1073260804,1073265410,817558,439525
7,00904b14b494,1073260804,1073262625,817558,439525 
8,00904b14b494,1073260804,1073265163,817558,439525 
9,00904b14b494,1073260804,1073263786,817558,439525
10,00022d1406df,1073260807,1073260809,820428,438735
0,00022d9064bc,1073260801,1073260803,819251,440006
1,00022dba8f51,1073260801,1073260803,819251,440006
2,00022de1c6c1,1073260801,1073260803,819251,440006
3,003065f30f37,1073260801,1073260803,819251,440006
4,00904b48a3b6,1073260801,1073260803,819251,440006
5,00904b83a0ea,1073260803,1073260810,819213,439954
6,00904b85d3cf,1073260803,1073261920,817526,439458
7,00904b14b494,1073260804,1073265410,817558,439525
8,00904b99499c,1073260804,1073262625,817558,439525
9,00904bb96e83,1073260804,1073265163,817558,439525
10,00904bf91b75,1073260804,1073263786,817558,439525

Expected Output: Index=None, Header=None

00022d9064bc,1073260801,1073260803,819251,440006
00022d9064bc,1073260803,1073260810,819213,439954
00904b4557d3,1073260803,1073261920,817526,439458
00022de73863,1073260804,1073265410,817558,439525
00904b14b494,1073260804,1073262625,817558,439525
00022d1406df,1073260807,1073260809,820428,438735
00022d9064bc,1073260801,1073260803,819251,440006
00022dba8f51,1073260801,1073260803,819251,440006
00022de1c6c1,1073260801,1073260803,819251,440006
003065f30f37,1073260801,1073260803,819251,440006
00904b48a3b6,1073260801,1073260803,819251,440006
00904b83a0ea,1073260803,1073260810,819213,439954
00904b85d3cf,1073260803,1073261920,817526,439458
00904b14b494,1073260804,1073265410,817558,439525
00904b99499c,1073260804,1073262625,817558,439525
00904bb96e83,1073260804,1073265163,817558,439525
00904bf91b75,1073260804,1073263786,817558,439525

Match every element of the row and if entire row is duplicate then keep the first and delete the rest of the duplicates.

Code:

from StringIO import StringIO
import pandas as pd

df = pd.read_csv(StringIO('input.csv'), index_col=[0], header=[' ','id_merged','time_1','time_2','gps_1or3','gps_2or4'])


df.drop_duplicates(keep='first')

df.to_csv('dart_small_final.csv',mode = 'a',header=False, index=False)

Edit One:

import csv
import pandas as pd

df = pd.read_csv('dart_small_final.csv', index_col=[0], header=[' ','id_merged','time_1','time_2','gps_1or3','gps_2or4'])


df.drop_duplicates(keep=first, inplace=True)
df.reset_index(drop=True, inplace=True)

df.to_csv('dart_final.csv', header=None, index=None)

Error:

Traceback (most recent call last):
  File "remove_dup.py", line 4, in <module>
    df = pd.read_csv('dart_small_final.csv', index_col=[0], header=[' ','id_merged','time_1','time_2','gps_1or3','gps_2or4'])
  File "/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.py", line 562, in parser_f
    return _read(filepath_or_buffer, kwds)
  File "/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.py", line 315, in _read
    parser = TextFileReader(filepath_or_buffer, **kwds)
  File "/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.py", line 645, in __init__
    self._make_engine(self.engine)
  File "/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.py", line 799, in _make_engine
    self._engine = CParserWrapper(self.f, **self.options)
  File "/usr/local/lib/python2.7/dist-packages/pandas/io/parsers.py", line 1213, in __init__
    self._reader = _parser.TextReader(src, **kwds)
  File "pandas/parser.pyx", line 504, in pandas.parser.TextReader.__cinit__ (pandas/parser.c:4950)
TypeError: cannot concatenate 'str' and 'int' objects