No, but the ability to mod completely trivializes story/TLSQ duels. I used Game Guardian to max out my attributes to 120. Since most quest duels aren't scaled, all it takes is a single "throw vial" attack and I win instantly. And even if I hadn't, the quest duels are laughably easy. They have scripted attack patterns that you can abuse to ensure an easy victory.
The Dueling Club, on the other hand, is a well-known scam even for modders. The AI that controls your opponent (yes, it's an AI, you're not fighting other players in real-time) has certain scripts running in the background that gives it an advantage on things like burns, heals, stuns, and bleeds. Your opponent's spell effects will almost always trigger when they attack you. Your spell effects will rarely trigger when you attack your opponent. Even if it's the same spell. It's literally designed to make you lose more frequently so that you spend more time (and coins) trying to win. And the spells you earn from Dueling Events aren't even useful in quest duels. Like I said in the first paragraph - quest duels have scripted attack patterns.
The Dueling Club is an entirely self-serving system. You can completely ignore it (aside from Y7 when you occasionally have to duel for Ministry tasks) and it will make absolutely no difference in your gameplay or story.