Hi,
The situation is as follows:
Garmin Instinct 2 Tactical ver. 15.02
Garmin Connect ver. 4.77
HRM-Pro Plus ver. 8.90
I noticed that in a particular situation that I will write about next - Garmin Connect records activities twice. I tested during both cycling and walking activities.
For once after an activity, before final confirming its completion (just after saving in GC) - you should select "download heart rate" (second choice from the end) in the data of the activity. Then after confirming the final activity - Garmin Connect saves the activity twice. Interestingly - in the watch there is still one activity (correctly), while in GC it is double. The double activity is included in the counting of statistics (distances, training status, load, etc.).
I think this is a software bug, occurring only in a specific case. It is also possible that this is related to the use of an external HRM heart rate sensor.
Mike