Best way to Indicate a item is shared or copied

I have a tree on my webpage that is used to display some folders and within these folders some items; These items can be copied from one node of the tree to another and also shared. when copied or shared the name remains the same, however i need to indicate visually that the item is a copy or a shared copy of a original item.

I use this icon image to display the original item

How can i change this to indicate its a copy or a shared item? Any input will be much appreciated.