Why are there two activities in PowerCenter for each of my runs?

There are two ways to collect data into the PowerCenter. The first way is by syncing Stryd with your phone. This run will not contain the GPS map trace and will contain all the pauses you took during the run. The second way is by syncing your watch account to the PowerCenter. This run will contain your the GPS map trace and will only include the data that your watch recorded. So, it will not include the pauses you took with your watch. If you would only like to see your watch data, you can skip the step of syncing your Stryd with the mobile app. You only need to sync your Garmin, Suunto, Polar, or Apple Watch sync to their respective platforms!