Hello, Smokey Cheese.
I can understand why getting duplicate notifications for messages you already read would be annoying. I’m happy to help lend a hand to figure out why you are receiving duplicate notifications on your Apple Watch.
To start, please make sure both your iOS and watchOS are up-to-date.
Update your iPhone, iPad, or iPod touch
Update your Apple Watch
Then, check to make sure your Apple Watch is set to mirror your iPhone.
"Customize your notification settings
- Open the Apple Watch app on your iPhone, then tap the My Watch tab.
- Tap Notifications.
- Tap an app. Different apps have different options. To use the same notification settings on your Apple Watch and iPhone, tap Mirror my iPhone. Some apps allow you to customize your notifications. When you customize, you can choose from these options:
- Allow Notifications: Notifications appear in Notification Center and your Apple Watch alerts you.
- Send to Notification Center: Notifications are sent directly to Notification Center without your Apple Watch alerting you.
- Notifications Off: The app sends no notifications.
4.If you customize an app's notifications, you can also group notifications from that app. Tap Notification grouping, then choose an option: Off, Automatically, or By app.
If you can't customize an app, you can still turn off its notifications. Scroll down to the Mirror iPhone Alerts From section and turn off the setting next to the app. “ Notifications on your Apple Watch
If the issue persists, don’t hesitate to respond to this thread.
All the best.