Submissions bug? 2 submissions from same customer, one never sent email notification and other missing content

Another bug is that submissions with ID 281236784151152875 and 281236850151819504 are obviously from one customer (and apparently same order), but for 281236784151152875 I never got any email notification and box.com did not get any files, and for 281236850151819504 everything worked fine, except it does not contain any files (it should). Is it possible that customer sends one submission, but it comes as this two with these bugs? Maybe he clicked send button twise or something? How we can avoid this?

Hi,

For SID: 281236784151152875 and 281236850151819504 - the user obviously forgot to upload the images so he returned to the form and submit again. 

You are using a custom recipient email address, please check the emails from SID: 281236784151152875 to your Spam Folder. The email may have been caught as spam. I would also suggest checking it using the webmail access instead of your email client (if you're using any). If no emails are there, we would advise to add our IP and Email Domains to your server whitelist: http://www.jotform.com/help/145-Whitelisting-JotMails-IP-Addresses.

Thanks