Kathy, your mom was partly correct you do need two for a good result. But male female. You should use a different variety maybe legacey or duke etc.
sorry for the missing words still trying to get the cell phone app to work.
You do not need a male and female only two different varieties.
and here the link I messed up http://ir.library.oregonstate.edu/jspui/bitstream/1957/12202/1/ec1304.pdf