Two authors same surname within one publication
I am writing my thesis in APA style. I have one publication where two authors have the same surname: Pfefferbaum, B. J., Reissman, D. B., Pfefferbaum, R. L., Klomp, R. W., & Gurwitch, R. H. (2007). Building Resilience to Mass Trauma Events.
But as I don`t cite any other publications of these authors, the two Pfefferbaums should appear without their first name in the in text citation, shouldn`t they?
What actually happens is that the first Pfefferbaum appears with initials. How can I change this?
Thank you very much!