Google Calendar has been updated to newer version which allows cross sync aka Synchronized notification dismissals across all your Android devices. Google has also provided bug fixes for some issues, mainly fix for crash when selecting colors for Exchange accounts.
In detail, What is Synchronized Notification dismissals ? Its also featured in other Google apps, most notably the Hangouts app. It syncs your notifications across all your devices once read or dismissed.
This new update comes to Google in the same way as with other of its applications, Hangouts, where it is already possible to sync notifications and conversations between different user devices.
You can hit the Play Store link below if you haven’t updated the Google Calendar app to latest version.
Source: Google Calendar Play Store.