RSS really has bad support for multiple authors, but I am subscribed to feeds that seem to go with it anyway.
AlterNet is such an example: http://feeds.feedblitz.com/alternet
<creator>Jill Iscol, Jimmie Briggs, AlterNet</creator>
I have also found a reference to multiple authors on Stack Overflow. Here too they mention using a comma to add more authors to a single item.
I’m not subscribed to any atom feeds using multiple author elements but I am just going to assume NewsBlur can handle those.
Could NewsBlur split RSS author fields on a comma? I don’t see any direct problems with this. Some feeds might use a comma in the author field to add honorifics or titles (Ph.D., M.D., &c) to names but this would not make for any filtering problems: flagging just the name without the title wouldn’t be a problem.
(While I guess an Regex like /,\s*[^aeiou]+\s*($||,)/ could make sure to keep things like ‘, Ph.D.’ attached to the name I’m afraid this will cause people to complain about too many edge cases: ‘Why is Ph.D. ignored but not MBA!’. And this is not worth hard-coding a list of honorifics into the code.)