This seems to be a bit of a corner case. I have two articles, with the same first author, B. G. Cook. The first article has a second author, S. C. Cook. The other article has two other authors (G. J. Smith and M. Tankersley).
What is the correct format? Following the format required for references with two first authors with the same surname (this is what biblatex-apa does):
B. G. Cook & Cook (2011); B. G. Cook & Cook (2011)
B. G. Cook, Smith & Tankersley (2012); B. G. Cook, et al. (2012)
Alternatively, since there would not be confusion between these two in either the first or later references:
Cook & Cook (2011); Cook & Cook (2011)
Cook, Smith & Tankersley (2012); Cook et al. (2012)
Or is there some other way?