Duplicate Killer Support – Help & Documentation

Cross-Form Duplicate Protection in WordPress Forms

A Complete Guide with Real-World Examples Duplicate form submissions are a common problem on WordPress websites. Most site owners focus on preventing duplicates inside a single form, but the real challenge often appears when multiple forms collect the same data…

WordPress Form POST Replay Protection: Why It Matters

When developers talk about duplicate form submissions in WordPress, the conversation usually focuses on users clicking the submit button twice. However, there is a less obvious technical issue that can cause the same form request to be processed multiple times:…

WooCommerce Checkout Blocks vs Classic Checkout: Why Duplicate Killer FREE Works Only With Shortcodes

If you enabled Duplicate Killer’s WooCommerce protection and it “does nothing”, you’re probably using WooCommerce Checkout Blocks. This is not a bug. It’s a technical difference between Classic Checkout (shortcode-based) and Checkout Blocks (block-based / Store API-based). Below is a…

Choose the Unique Fields in WordPress Forms (How It Works)

One of the most important steps in preventing duplicate submissions is choosing the right fields to validate. The Choose the unique fields in WordPress forms feature allows you to select exactly which form fields should be checked for duplicates before…

Limit Submissions by IP Address in WordPress (Free & PRO)

Repeated form submissions don’t always come from cookies or browser refreshes. Sometimes, users try to submit the same form multiple times from the same network. That’s where Limit submissions by IP address in WordPress becomes essential. This feature restricts form…

Unique Entries per User in WordPress: How to Use It

Duplicate form submissions are not always caused by multiple users.Sometimes, the same user submits the same form multiple times — intentionally or by mistake. The Unique entries per user in WordPress feature solves exactly this problem. Instead of blocking duplicate…

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