Just for fun consider an ideal xfrmr with a primary of N turns and two secondaries of N turns each.
Now load one secondary with Z1 and the other with Z2. What is the reflected load?
Now connect the secondaries in series and leave Z1 and Z2 connected. What is the reflected load?
Now disconnect Z1 and Z2 from the center tap but leave them connected in series. What is the reflected load?
Now load one secondary with Z1 and the other with Z2. What is the reflected load?
Now connect the secondaries in series and leave Z1 and Z2 connected. What is the reflected load?
Now disconnect Z1 and Z2 from the center tap but leave them connected in series. What is the reflected load?