Why isn't Firefox submitting my form twice?

HTML/JS Here: http://pastebin.com/JrtfeAtw PHP Here: http://pastebin.com/EcRHCwmY Based on Ajax F1's tutorial here: www.ajaxf1.com/tutorial/ajax-file-upload-tutorial.html

Anyway, my problem. In Chrome, this works fine. However, in Firefox, it will upload the first file no problem, and begin upload开发者_JAVA技巧ing the second one. I've traced it in Firebug and it definitely calls form.submit() on the correct form, and the form has the correct fields in it, but for some reason my form never gets submitted.

Is this because I'm submitting the same form twice? And if so, is there a workaround that anyone knows of?

Cheers!

I have no explanation for this, however, setting the source of the iFrame to about:blank between each image upload fixed the issue.