Incoming phone calls, like other notifications appear on your Apple Watch or iPhone, but not both. If your iPhone is unlocked, you get notifications on your iPhone instead of your Apple Watch. If your iPhone is locked or asleep, you get notifications on your Apple Watch, unless your Apple Watch is locked.
Iff you don't want incoming phone calls to appear kn the watch, see the 'How to mute or turn off an app's notifications on your Apple Watch' section in:
Notifications on your Apple Watch - Apple Support
To turn off the phone's notifications on the watch:
- Open the Apple Watch app on your iPhone, then tap the My Watch tab.
- Tap Notifications.
- Scroll down to Phone, select it, then Custom, and turn off Notifications.