In the past week, syncing my fenix 5S to my Garmin Connect mobile app on my iPhone has resulted in activities being duplicated. Strava seems to be smart enough to only pull up a single activity record, but I'm still showing duplicates of my workouts. Interestingly, the records are not 100% identical so it doesn't seem that they are cloned copies. Instead, one activity will show as "Treadmill Running" while the second record of the same activity will show as "<Location> Running" with very slight variations by a second or two. This is entirely new, and I didn't do anything to change my settings.