To clarify, you want users of a stream to be able to duplicate apps or to duplicate streams?
If you want to enable users to duplicate apps, you need to give them access to do that in QMC via a security rule. It is not possible to duplicate apps from the hub published to any stream.
For this situation look at the following:
and look at the qmcsection items.
If you are talking about duplicating sheets and publishing sheets within in an app, then look at the regular resources.
In addition, here is a webinar on security rules that you may find helpful: SenseSecurityRules.mp4 - Google Drive