LibAnswers: APA FAQs

According to the 7th edition of the Publication Manual of the American Psychological Association:

"To differentiate references with the same author and year, put a lowercase letter after the year in both the in-text citation and the reference list entry"(American Psychological Association, 2020, p. 305).

So, if you have two different papers from the exact same authors written in 2016, for example, you would have 2016a & 2016b, and you would include the a & b in both the in-text citation and the reference list entry. 

When listing on the reference list, works that include the year only for date of publication would go before works that include a month and/or year of publication(American Psychological Association, 2020, p. 305).

For more information:

https://apastyle.apa.org/style-grammar-guidelines/citations/basic-principles/same-year-author

References

American Psychological Association. (2020). Publication manual of the American Psychological Association (7th ed.). https://doi.org/10.1037/0000165-000