Duplicate submissions are one of the most common issues in WordPress forms. They affect data quality, analytics, lead management, and automation workflows. To address this problem without adding friction (like CAPTCHAs), Duplicate Killer includes an optional cookie-based protection feature.

This article explains how the cookie feature works, what it does and does not do, and what site owners should configure to remain GDPR-compliant.

What Is the Duplicate Killer Unique user per form?

When enabled, Duplicate Killer creates a small functional cookie in the visitor’s browser. This cookie acts as a unique, anonymous browser identifier used only to detect and prevent duplicate form submissions.

• The cookie is generated client-side.
• It contains a random, non-identifiable token.
• It is scoped per form, not globally.
• It is never shared with third parties.

The cookie exists solely to answer one question: “Has this browser already submitted this specific form?”

What the Cookie Does Not Do

To avoid confusion, it is important to clarify what this cookie is not used for:

• It does not track users across pages or sessions.
• It does not store names, emails, IP addresses, or personal data.
• It does not enable analytics, profiling, or advertising.
• It does not identify a real person.

The cookie’s only purpose is technical integrity and abuse prevention.

Per-Form Cookies (Why This Matters)

Duplicate Killer does not use a single global cookie. Instead, a separate cookie is created for each form where cookie protection is explicitly enabled.

Example cookie names:

• dk_form_cookie_cf7_72
• dk_form_cookie_elementor_forms_1fc7fb0
• dk_form_cookie_formidable_contact-us_2

This design ensures:

• Submitting one form does not block other forms.
• Each form can have its own expiration period.
• Cookie usage is minimized to the strict technical need.

Is This Cookie GDPR-Compliant?

From a GDPR perspective, this cookie generally falls under the category of functional or strictly necessary cookies, because:

• It is required to prevent abuse and duplicate submissions.
• It supports a user-requested action (form submission).
• It does not process personal data.

However, final responsibility always lies with the site owner, because cookie classification and consent requirements may vary by jurisdiction, regulatory interpretation, and local legal advice.

Recommended GDPR-Safe Configuration (Best Practice)

To remain on the safest possible legal ground, Duplicate Killer is designed to allow explicit control over when cookies are created.

Recommended approach for maximum compliance:

• Enable cookie protection only for forms that require it.
• Set the cookie duration to the minimum practical number of days.
• Ensure the cookie is categorized as Functional or Necessary in your cookie banner.
• If your site uses a consent management platform (CMP), configure it so functional cookies are allowed only after user consent.

If you are unsure whether consent is required in your case, the safest option is to require functional cookie consent before enabling the feature.

Transparency for Visitors

For full transparency, it is recommended to mention this cookie in your Cookie Policy. A simple and clear description is sufficient.

Example wording:

Duplicate Killer uses a functional cookie to prevent duplicate form submissions. This cookie does not store personal data and is not used for tracking or advertising.

Developer Responsibility vs. Site Owner Responsibility

Duplicate Killer provides the technical tools to prevent duplicate submissions in a privacy-respecting way.

The plugin does not automatically decide your legal obligations. Instead:

• The plugin limits cookie usage to the strict technical minimum.
• The site owner decides whether and how the cookie is enabled.
• The site owner is responsible for consent configuration and legal compliance.

This separation ensures flexibility while allowing site owners to comply with GDPR, ePrivacy, and similar regulations according to their specific requirements.

Summary

• Duplicate Killer cookies are functional and per-form.
• No personal data is stored or transmitted.
• The feature improves data quality without user friction.
• For maximum legal safety, enable cookies only after functional consent.

Used correctly, the cookie-based protection offers a clean, privacy-first alternative to CAPTCHAs while maintaining full control and transparency.