Biblatex cannot separate the first and the second authors

Question

I am using biblatex for my citations as the below code shows:

\usepackage[
  backend=biber,
  style=authoryear,
  dashed=false,
  isbn=false,
  uniquename=init,
  giveninits=true,
  maxbibnames=99,
  maxcitenames=2,
]{biblatex}

By using the option maxcitenames=2, I would like to have references with more than 3 authors cited as "{First author} et al.".

For most of the references, I can get the desired citation style. However, for some references, biblatex cannot distinguish the first and the second authors. As a result, I have some in-text citations as "{First author}, {Second author}, et al.", which are very weird.

The following code show my entry in the bib file.

@article{Chiputwa2015,
author = {Chiputwa, Brian and Spielman, David J. and Qaim, Matin},
doi = {http://dx.doi.org/10.1016/j.worlddev.2014.09.006},
journal = {World Development},
pages = {400--412},
title = {Food standards, certification, and poverty among coffee farmers in 
Uganda},
volume = {66},
year = {2015}
}

And the output that I got was "(Chiputwa, Spielman, et al., 2015)". I would like to get it as "(Chiputwa et al., 2015)". I tried to set maxcitenames = 1, but got a similar result. So I guess the problem is the biblatex cannot separate the first two authors.