Insert values into a column in the same table based on a criteria

[klllmmm]

I need your help to insert vales into my table based on a criteria.
My dataframe is as follows

df = pd.DataFrame([['2016-04-19',533247,1975000,np.nan], ['2016-04-19',533247,np.nan,1975000],['2016-05-05',np.nan,1947293.42,np.nan],['2016-05-05',np.nan,np.nan,1947293.42],['2016-06-03',535199,1930000,np.nan],['2016-06-04',535199,np.nan,1930000],['2016-08-04',np.nan,195000,np.nan],['2016-08-05',628490,5000,np.nan],['2016-08-05',628490,np.nan,5000],['2016-12-30',750200,15000,np.nan],['2016-12-31',326500,np.nan,15000]], columns=['DATE','CHQNO','Deposit','Withdrawal'])

I need to insert a value as 'RTN' into a new column call 'Status' if there are two records with same value in df[CHQNO] column & same value in df[Deposit] & df[Withdrawal] columns.

I'm expecting a dataframe like this

Output:
DATE        CHQNO Deposit        Withdrawal Status
0 2016-04-19 533247 1975000.0                 RTN
1 2016-04-19 533247                1975000.0 RTN
2 2016-05-05       1947293.42 
3 2016-05-05                        1947293.42 
4 2016-06-03 535199 1930000.0                 RTN
5 2016-06-04 535199                 1930000.0 RTN
6 2016-08-04         195000.0 
7 2016-08-05 628490    5000.0                 RTN
8 2016-08-05 628490                     5000.0 RTN
9 2016-12-30 750200 15000.0 
10 2016-12-31 326500                    15000.0

Thank you very much.
Moderator Larz60+: Please use output tags (I added this time)