Check if object is an instance

Hi,

I can't seem to find a way to check if an object is an instance or not. I know I can use InstanceMgr.getInstances to get the number of instances for the specified object, but it's not what I'm looking for. RefHierarchy.isRefTargetInstanced is more like what I want, except it returns true for every instanced objects, even the "original" one (from which other objects are instanced). Is this normal ? The same goes for references...

Is there a way to get only instanced objects without the original one ?

I hope you'll understand what I mean,

Thanks