Calibre adding 287 ebooks for 1 ebook sent

Calibre detected my Sony PRS300 ereader.

I highlighted the book (epub) I wanted to send.

Then I did the two-step process of:
1)Send to Device
2)Send to main memory

with the one single (small-ish, well under 1MB) epub.

The path Calibre put the epub on in the ereader was:

Database>Media>books>the epub's folder>the epub file

I waited for the green checkmark to appear.

Everything looked good but when I disconnected the ereader it took forever to load and I had 287 copies of that single book on the ereader.

Anybody have any idea what might be happening and how I can get it to work normally?

Thanks.