Alex, to be sure, you want to copy a Material Editor component to another?
The why I do it is to go into the DTE for the component that you want to copy (using TheBryster's steps). Next to the Combination box, click the top brass colored gadget which loads the DTE texture library. Save the texture in any of the sub-cats. Exit the DTE and click in a dot in an empty ME component to create a new one. Then click the down arrow at the top right of the component and from the popup select the texture you just saved.
Hope that's what you were looking for.
Best;
Dan