A158: No
A159: Page 160, Table 8-10, Player's Handbook for the primary attacks. Additional off-hand iterative attacks (via imp twf, greater twf, etc) follow the same rules for normal attacks: Each additional iterative is made at an additional -5 (ie, off-hand attack one has standard twf penalties, off-hand attack two has standard twf penalties and another -5, three is standard with another -10, etc.).
Edit: GAH! NINJA'D BY AN EDIT! CURSE YOU CANTRIPN!