How are the Cell Ids (and with that the structure in the design tree) built in CQ5?
The Cell Id is always created from the path the component is included with.
For example the Cell Id of a component
/apps/myApp/components/myComponent included by
<cq:include path="myPath" resourceType="myApp/components/myComponent" /> i.e. in your pagecomponent is myPath.
Also the name of the Node created in the design tree is myPath.
There are two exceptions:
<cq:include>and represent the start of the component includes
For these two exceptions the component label (in our example myComponent) is used as the Cell Id.
If the property
cq:cellName in the component definition is set, the value of this property is taken as Cell Id.
Therefor with this property
cq:cellName you can enforce separate Cell Ids for different components with the same label (i.e in a paragraph system).
It's also possible to enforce the same Cell Id for components with different labels, for example if you want to use the same design for your homepage- and contentpage-component.
Note: For CQ 5.2 the property
cq:cellName is only respected for non toplevel components. This is fixed in CQ 5.2.1