How to Contact Form 7 Prevent Duplicate Submissions
Install cfdb7 unique field plugin. Then we need to add a shortcode “unique” after the submit button shortcode.
It will prevent multiple submissions.
Example: [unique email, your-phone]
How to Change the Error Message Unique Field (CF7)?
We can change contact form 7 email already exists error message from wp-admin.
Go to wp-admin > contact form 7 > select form > messages > search “Field value that the sender entered is already submitted”. You can edit and save the contact form.