This article explains what you can do if you have a need to duplicate a container.
Containers cannot be duplicated, but it is possible to duplicate pages and single widgets.
In other words, if you are in need of duplicating a specific container (and it's widgets), you might want to consider duplicating it one widget at a time and then creating a new container to which those duplicated pages can be put under.
If you'd like to duplicate a huge number of containers, you can consider the option to duplicate a whole page instead, and then delete those widgets and containers that are not needed.
You will find instructions on both widget and page duplication from Help center.