Why did customers get duplicate Shopify order-confirmation text messages?

Duplicate order-confirmation texts can happen when Shopify's built-in SMS and a third-party app both send a confirmation for the same order. I'd compare the sender, wording, and order number on the two messages, then check the confirmation settings in your SMS apps. If an app is already handling those confirmations, Shopify says to deactivate its own version to prevent duplicates: open Settings, then Notifications, Customer notifications, Order confirmation, and the SMS tab. Deactivate Shopify order confirmation SMS there after confirming the app will still deliver the message you want. If Shopify's SMS is already off, keep checking the app's sending history instead of assuming Shopify sent the second text. Also separate this from SMS marketing signup or a Shop app push notification; those aren't the same thing as an order-confirmation text.