Duplicate runs in Apple Health: why and how to fix

You finish a 10 km run and Health shows 20 km. Nothing ran twice. Two apps each wrote the same workout.

How it happens

Health accepts workouts from any app you allowed. The common pairs:

• Apple Watch Workout app plus Strava on the phone. Both recorded, both wrote.
• Apple Watch plus Garmin Connect when you wore both watches.
• A watch app plus Strava, both set to write to Health. Strava passes on runs it received from a Garmin, Coros or other watch, so the watch's own app and Strava each write a copy. Turn off Send to Health in Strava, or the Health sync in the watch app.

Find the source

Health app, Browse, Activity, Workouts. Tap a run and scroll to Source. Do it for both copies. Now you know which two apps are writing.

Stop it at the source

Pick one recorder per run. Then in the app you do not want writing, turn off Workouts in its Health permissions: in the Health app, tap your profile picture, then Apps, choose the app and switch off Workouts. The app keeps working. It just stops writing runs.

Or let Runtile merge them

Runtile deduplicates on its own. Two runs whose start and end both fall within a minute of each other are treated as one, and the copy with the larger distance is kept. The import screen shows how many were merged, and Settings, Duplicates lists every merge so you can keep or split any of them.