Multiple file attachments

I’ve successfully created a form where the submitter can upload a file and I successfully receive the file in an email. I’ve read the File Uploading and Attachment page, and have [your-file][your-another-file] in the File Attachments field on the Mail tab, but when I test the form and try to upload a second file, it replaces the first file. Can you see what I am doing incorrectly? Thank you.