I'm gathering information for the RSS Advisory Board on the issue of multiple item enclosures in an RSS 2.0 feed.
On first reading, it appears to me that an item must contain either zero or one enclosure elements, but I have to do more research about how existing implementors have interpreted the specification.
I created a test feed that contains a single item with two MP3 enclosures. Surprisingly, this feed validates in the Feed Validator and RSS Validator. I'd like to find out if any podcasting-capable aggregators retrieve and present both of the feed's audio files.