Elizabeth Vogt of Vashon Island, WA wrote about her bees building two combs beside Pierco foundation. I believe its a combination of bee space and the plastic not being attractive. If you like this type of comb honey, use empty frames(no foundation). I use 9 frame medium supers for honey. My extractor is 4 frame. I was always needing to deal with the extra frame until I started using the centre frame of each honey super for cut comb. The centre frame is normally finished first and can be removed before the super is full( insert another empty frame in its place) or left until the super is full. I used full sheets of cut comb foundation at first, cutting back to part sheets, then to no foundation at all. IN A GOOD HONEY FLOW the bees draw out the frame in drone sized comb, then fill it and cap it quickly. Bob Darrell Caledon Ontario Canada 80W44N