Updated for version 1.0
Viewing post in Battle Weaknesses (Base Game + DLC)
You can't re-fight Dursed Dodoro if he can't be booked in the dictionary (the little square that says "rent a room" shouldn't be greyed out).
The regular Dodoro can be found on Solitude in the area where you mine for black ore. For that one just keep entering and leaving the battle until he appears as he is kinda rare.