Duplicate Killer – Prevent Duplicate Form Submissions

Duplicate Killer prevents repeated submissions in WordPress forms. Choose which supported fields must be unique, such as an email address, phone number or text value. When a matching value has already been saved by Duplicate Killer, the plugin blocks the repeated submission and displays your message.

Use it to reduce duplicate leads, repeated contact requests and multiple registrations with the same email address. No CAPTCHA is required for duplicate checks.

Reduce repeated form spam without adding CAPTCHA

Some unwanted submissions repeat the same email address, phone number or other field value. Duplicate Killer can block these repeated values in supported WordPress forms. Optional IP-based limits can also restrict further submissions from the same IP address during your chosen protection period.

Duplicate Killer adds duplicate submission protection, not general bot detection. Spam using new values and different IP addresses may still pass these checks.

When is Duplicate Killer useful?

• Contact forms: reduce repeated requests using the same email address or phone number.
• Registration forms: block another registration with an email address already saved by Duplicate Killer.
• Lead forms: reduce repeated entries before your team follows up.
• Time-based restrictions: allow the same value again after a protection period in minutes, hours or days.
• Multiple forms with PRO: check selected forms within the same supported form plugin.

Duplicate Killer checks submitted values. It does not verify that an email address belongs to the visitor or guarantee one entry per person.

Supported form plugins

Duplicate Killer adds duplicate submission protection to existing forms. It does not create forms. Available fields depend on the integration. The Free version allows configuration of the most recently created form in each supported form plugin.

Contact Form 7: prevent duplicate entries

Block repeated Contact Form 7 submissions using selected fields, such as email, phone or text. Show your duplicate message through Classic Message or Modern Popup Mode.

Elementor Forms: prevent duplicate submissions

Add duplicate checks to forms built with the Elementor Pro Form widget. Duplicate Killer PRO also includes Group Mode for forms that share the same Form Name.

Forminator: control repeated submissions

Choose supported Forminator fields to check for repeated values. Set a protection period when the same value should be allowed again after a certain time.

WPForms Lite: add duplicate-field checks

Use Duplicate Killer with WPForms Lite to check selected fields against entries saved by Duplicate Killer. Visitors receive your configured message when a duplicate is blocked.

Formidable Forms: require unique field values

Apply duplicate checks to supported Formidable Forms fields. For example, check an email field to reduce repeated registrations with the same address.

Ninja Forms: block repeated form values

Add duplicate protection to supported Ninja Forms fields. Choose the values to check and explain blocked submissions with your own duplicate message.

Breakdance Forms: protect your existing forms

Check supported fields in forms built with the Breakdance Form Builder. Configure duplicate protection without replacing your existing form.

Fluent Forms: reduce duplicate leads

Check selected Fluent Forms fields for values already saved by Duplicate Killer. Use this to reduce repeated contact requests or lead submissions.

MetForm: duplicate protection in beta

Add duplicate checks and Modern Popup Mode to supported MetForm forms. Submission details can include links to uploaded files. Test MetForm Pro payment forms and external integrations on a staging site before use.

WordPress form submission limits and IP protection

• Select the fields to check for duplicate values.
• Set duplicate protection periods in days, hours and minutes.
• Configure IP-based submission limits separately.
• Use optional browser cookie protection.
• Review saved submissions in your WordPress dashboard.
• Display the saved submission count with a shortcode.

Field checks and IP limits serve different purposes. Field checks look for repeated values, such as an email address. IP limits restrict submissions from the same IP address, even when the submitted values differ. Configure them separately for your form.

People on a shared network may use the same public IP address. Choose IP restrictions carefully when several visitors may submit from an office, school or household.

Example: block the same email for 24 hours

Select the email field in your protected form and set the duplicate protection period to 1 day. Save your settings, then submit a new email address. Another submission with that email will be blocked during the protection period.

Other enabled rules, such as IP limits, are checked separately.

Classic Message or Modern Popup Mode

Keep a standard duplicate error message or display a custom popup. Modern Popup Mode supports formatted text, links and colors. Preview your popup in the settings before saving. Existing forms keep Classic Message by default.

Free and PRO

The Free version lets you configure the most recently created form in each supported form plugin, with custom protection settings and messages.

Duplicate Killer PRO lets you protect multiple forms with separate settings. Cross-Form Duplicate Protection checks selected forms within the same supported form plugin. Elementor Group Mode groups forms that share the same Form Name.

Use separate rules when your contact form and registration form have different requirements. Use Cross-Form Duplicate Protection when several forms collect entries for the same campaign and should share duplicate checks.

For Elementor sites that reuse forms with the same Form Name, Group Mode helps apply protection across those forms.

Compare Free and PRO

WooCommerce duplicate order protection

The Free version also includes duplicate order protection for WooCommerce Classic Checkout, with a 60-second protection window. PRO adds Checkout Blocks support, a configurable protection window and additional reporting tools.