When it comes to preventing users from submitting the same form multiple times with the same data, the “Already Submitted” extension is quite handy. You can use the extension to define which input values need to be unique for each submission to be successful.
Enabling the Already Submitted Extension #
In this section, you will learn how to enable the “Already Submitted” extension. First, visit the “HT CF7 Extension” menu from your dashboard and open the “Extensions” tab.
In the tab, you can find a switcher option to enable the “Already Submitted” extension. After you enable the extension, don't forget to save the settings.

Configuration of the Already Submitted Extension #
Before configuring the extension, head over to the edit screen of the form where you want to apply the extension. Once you visit the edit screen, you can notice a new tag named “HT Unique Fields“. If you click the tag, you will see a popup including the essential options to configure the extension.
For instance, you can see the names of the available fields in your contact form. Next, copy the field name(s) for which you want to prevent duplicate data and paste them into the “Prevent duplicates value for” field. If the number of fields is more than one, separate the field names with a comma. Now that you have configured the extension, insert the tag into your form.

After inserting the tag, your form code will look like this.

After completing the setup of the Already Submitted Extension #
Your name and your email field are not accepted because the name and email of “John” and “[email protected]” have already been submitted to the form. So this name and email will no longer be added again. Hence no duplicate entries will be found.
If you watch the video above, you'll notice that the name and email fields are not accepting values as there is already been a submission with the same name and email address. This is how you can prevent duplicate entries using the “Already Submitted” extension.