I want to create several rule based styles on a layer. The rules are very similar, therefore I copy the first one then paste it multiple times and make the slight modifications on the pasted ones. The problem is that the pasted rules don't seem to be independent, rather they seem like they'd be linked somehow. For example, if I turn off the visibility on one, all the others disappear too. It is suspicious that in the project file all the pasted rules have the same "key" string (whatever it is), but the original rule has a different one. Excuse me for the laymans wording, I am not a qgis pro. The version is QGIS Desktop 2.18.4
The best way to apply same rule on several files is to save the style layer as a new QML file from Layer
Properties -> Style (Lower left button) -> Save Style -> QGIS Layer Style File
and load it again on other layers from
Properties -> Style (Lower left button) -> Load Style
Then you can adjust the style for each file as you like.
There is also a MultiQml plugin that can be used to apply the same style on several layers at the same time.