I don't know how it is even possible, but...
the bigger constuction site is Timberhouse,
the smaller one is Chicken Coop, planned to be built at right front corner
the chicken coop image is a ghost preview, planned to be built at left front corner, BUT impossible due to "this site is occupied" error.
Clean and fresh vanilla client, plain construction w/o any additioanl keys or console commands involved.