The model numbers of the Antenna Craft Antennas??
The number one reason for 'stacking' antennas is to increase reception and the antennas and aimed in the same direction.
Are the antennas aimed the same direction??
When I know the model numbers of the antennas , I will recommend reception with 1 or 2 antennas and ->No Antenna Rotator , Antenna rotators are Not channel surfing friendly , must wait for antenna to rotate.
What antennas look the most like the antennas you have ,
http://www.kyes.com/antenna/pointing/pointing.html