I've found that Last, First prevents any number of issues when it comes to multiple names. Without the comma there are more ambiguities. See [this essay](http://nwalsh.com/tex/texhelp/bibtx-23.html) for a good description. It has been referenced on [tex exchange](https://tex.stackexchange.com/questions/557/how-should-i-type-author-names-in-a-bib-file), for what that is worth,