Same content, but several instances

I am looking for following solution and want to ask, how this is possible:

Using 2 or more instances with the same content (posts, pages, comments, categories), but different settings for WordPress (themes, widgets, plugins).

I tried to copy all tables of the WP-DB (“Master”) to another (“Slave”), but left only the wp_options and used an own one for that new instance. This worked and would fit my need.

The only problem: If someone comments at the second instance and I do a DB-replication from “Master” to “Slave”, these comments are overwritten; also there would be a time delay until the updates of the “Master” are copied to “Slave”.

Is there a solution to use several “Option-tables” for different WP-Instances, but all other tables with content for 2 or more WP-installations?

Thanks for help!