The Collaborative International Dictionary of English v.0.48:

Dipteral \Dip"ter*al\, a.
   1. (Zool.) Having two wings only; belonging to the order
      Diptera.
      [1913 Webster]

   2. (Anc. Arch.) Having a double row of columns on each on the
      flanks, as well as in front and rear; -- said of a temple.
      [1913 Webster]