dual personality;  split personality
 twofold and threefold;  doubled and redoubled
 dual structure;  double structure
 instrumental duet;  instrumental duo
 double circle (indicating "very good" on a piece of school work)
 double helix (structure of DNA)
 double-glazed window;  double window;  storm window
 someone with a dual personality
 double torture;  double pain;  double hardship;  double whammy
 double star;  visual double
 double helix (structure of DNA)
 dual nationality;  dual citizenship
 double weave;  double cloth
 redundant keigo (i.e. improper use of the -rareru honorific form together with an honorific verb such as ossharu)
 double weave;  double cloth
 issuing (the same receipt) twice;  issuing duplicate (receipts)
 dual attachment concentrator
 double standard of morality