Duplicate Killer Support – Help & Documentation

The Hidden Cost of Duplicate Orders During Black Friday

Duplicate WooCommerce orders become a massive problem during Black Friday sales. Customers click checkout buttons multiple times, pages freeze under heavy traffic, and stores suddenly face duplicate payments, refunds, and inaccurate analytics. But for many WooCommerce stores, it also creates…

How to Stop Duplicate WooCommerce Orders (Without Annoying Your Customers)

Duplicate WooCommerce orders are more common than most store owners realize. A customer clicks the “Place Order” button twice because the page freezes for a second.Another refreshes the checkout page after payment.Someone on mobile taps repeatedly because they think nothing…

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…

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