Why Did WooCommerce Create Duplicate Renewal Orders?

Why This Happens

Action Scheduler is generally reliable about not double-processing its own queued actions, but that protection can break down when multiple independent cron triggers exist on the same site — for example, WordPress's own pseudo-cron still enabled alongside a separately configured real server cron job both calling wp-cron.php. Under the right timing, both can end up processing overlapping due actions close together.

Common Causes

• Multiple cron triggers configured simultaneously, most often WordPress's default pseudo-cron left active alongside a real server cron job added later without disabling the default.
• A staging or backup copy of the site also running cron against what turns out to be a shared or restored database, effectively creating a second scheduler acting on the same data (related to the staging-site renewal risk covered separately, though the failure mode here is a duplicate rather than an unintended live charge).
• Custom code or a plugin manually triggering a renewal without checking whether the scheduled action for that cycle has already run.
• A race condition under high load, rare but possible on a site processing many subscriptions if the scheduler's own locking mechanism is affected by server-level concurrency issues.

How to Fix It

1. Check for multiple active cron triggers. If a real server cron job calling wp-cron.php is configured, confirm WordPress's own pseudo-cron is disabled via define('DISABLE_WP_CRON', true); in wp-config.php — running both is the single most common cause.
2. Check WooCommerce → Status → Scheduled Actions for the specific subscription's renewal action history, looking for two completed actions close together in time.
3. Rule out a stray staging/backup environment that might be running its own cron against the same or a recently cloned database.
4. Refund and cancel the erroneous duplicate order once confirmed, and fix the underlying cause so it doesn't recur on the next billing cycle.

See WooCommerce fixes if duplicate renewals are happening repeatedly rather than as a one-off, since that points at a structural scheduling issue worth resolving properly.