The class node in the XML definition file is the component's handler, meaning it is what define its behaviour.
No way you can have 2 different behaviours at once as it is one component (You could have different behaviours, based on the scope or by filtering in your XML file though).
What you need to do is create your own class that extends the ImportContent class and in there, wherever you need it, use the other class.
My explanation is not very clear but as yours is not either, we should understand each other
If I'd have time, I would give you a detailed description but I don't think my boss would appreciate my time been given away for free
Check the WDK documentation to see how to extend and modify the behaviour of a component