Duplicating of the old orders

Hello. I'm a web-developer and an experienced user of your service. My client has a problem with applications (orders) from your service. He received a lot of duplicates of the past orders. I've checked step-by-step email, receiver and the orders in the history of my form. In the history's logs I found these orders (as a new copies), but people who used this form in web didn't send these orders. 

Can you resolve this problem and inform me, why past orders are now duplicating?

If the duplicate submissions were severe or a lot, it is possible also that these were spam submissions only. It is possible that spam bots have identified your form URL and were not able to use to send spam submissions.

You can block spam submissions by adding the Captcha field on your form. The captcha field will require actual human interruption when filling in the form.

Another option is to set Unique submissions on the form. This option will prevent submission from the same user when enabled.

You can remove the duplicate submission by using the Search box in the View submission grid. You can filter submissions using the Search box.

Hope this help. Let us know if there is more we can assist you with.