Duplicated rows when merging dataframes in python

Question

I am currently merging 2 dataframes with an outer join, but after merging, I see all the rows are duplicated even when the columns I did the merge upon contain the same values.

Answer 1

list_2_nodups = list_2.drop_duplicates()
pd.merge(list_1 , list_2_nodups , on=['email_address'])

The duplicate rows are expected. Each john smith in list_1 matches with each john smith in list_2. I had to drop the duplicates in one of the lists. I chose list_2.