Because of lack of time I have decided to open source this app. You can find its source code on Github under a GPLv3 license. Hopefully someone can pick up where I left and continue its development, since it has a fair share of enthusiastic users. Do you have multiple calendars?
Jeroen van Disseldorp is the developer of Calendar Cloner that relates to the Productivity category. The tool has been downloaded and installed by over 0,5K users and the latest update was released on Feb 3, 2017. On Google Play, this application has been rated 3.9 by its users.
Download the installation package of Calendar Cloner 3.87 at no cost and have a look at users' reviews on Droid Informer. The app works flawlessly on Android 4.0.3 and above. The app is totally secure for downloading.
The way users see it, this application has such a disadvantage as a lack of support.