I found both of these with what one could call “random-walk playing” with polyhedral-manipulation software, Stella 4d, available here, with a free trial-download available. In the figure above, both compound components are skewed cubes, while the image below shows a compound of three skewed tetrahedra. Since (2)(6) = (3)(4) = 12, each of these compounds has the same total number of faces, although, of course, the number of faces per component polyhedron varies from one compound to the other.