Can I have two feeds from one website?

Do both feeds have the same title? - that will produce the error you see. You will have to change the title of the second feed: obviously its URL is already different and I wouldn't have thought that the fact that they are both on the same server would matter.

Dificult to say. I can't promise anything, but if you like to post the URLs of both feeds (make it clear which is which) I'll see whether anything strikes me.

The only thing I can suggest is that the problem may lie in the 'link' tag being the same:

http://www.audio-byte.co.uk

You should find another URL to put in the new feed. You could go to http://tinyurl.com and create a forwarding link there to the same URL so that the effect would be the same but the URL would be different.

Now that you've tried to submit the feed once you will probably get the same error again anyway (there is a bug which will tell you that a feed which has been removed or rejected has already been submitted), so you will need to change the title slightly (for example put 'The' at the begining and change the colon to a dash) - you can always change it back once the podcast is accepted.

You still have the same 'link' tag in the new feed - you must have entered this somewhere in WordPress as your website (unless you did this using Smartcast in Feedburner) so you need to change it there as I suggested. Then you're going to have to change the title again, I'm afraid.

The 'link' tag in http://feeds.feedburner.com/ExpertInterviewSeriesPodcasts still leads to http://www.audio-byte.co.uk as before: I don't know what you would have to do in WordPress to change this.

More seriously, your feed now has no episodes - you must have deleted the one which was there when I checked yesterday evening.

The link tag is still the same. Only episode 1 has a media file referenced. If your latest episode doesn't have a media file, the Store will complain that it can't download your files as it appears to check only the most recent one.

The link tag will only change when you change wherever in WordPress or Feedburner you entered the URL in the first place. I would advise not trying to submit until you have checked that the tag has changed. You can do this by entering the URL in http://www.feedvalidator.org and then using your browser's search field to find the tag - or you could post the feed URL here again and I'll check it.