If you installed two left wings, or two right wings, but installed the
"wrong one" facing backwards, it might be perfect for thermaling in a tight
column of air - as long as you made sure you always went in the correct
direction.

It could also be good for flat spin recovery - if you made sure you spun it
in the correct direction.

Tow rope attachment might be somewhere on the rear facing wing, to help it
launch straight, althugh it might require some experimentation.

Colin