Question

I want to create a RSS feed for a podcast with more than one author. Shall I write

<item>
    ...
    <itunes:author>Person 1, Person 2</itunes:author>
    ...
</item>

or

<item>
    ...
    <itunes:author>Person 1</itunes:author>
    <itunes:author>Person 2</itunes:author>
    ...
</item>

?

Answer 1

If multiple author names were allowed, they would be nested within a general author parent, like so (or something similar):

<itunes:authors>
    <itunes:author>Person 1</itunes:author>
    <itunes:author>Person 2</itunes:author>
</itunes:authors>

The specification document (http://www.apple.com/itunes/podcasts/specs.html#author) states a single itunes:author element, which means option 1 in your question is the way to go:

<item>
    ...
    <itunes:author>Person 1, Person 2</itunes:author>
    ...
</item>

You can always test your feed through an online validation tool: http://feedvalidator.org/