As Jo said, I would strongly suggest that you offer a separate bottle of clean water in addition to any bottles you've added anything to. You never know when someone might suddenly develop a dislike for the flavor and will go without. Also, if they're eating a diet specifically designed for rats, they don't need any added vitamins. Getting more than their daily dose could have a negative effect long term. If you offer them as a monthly thing, or just when they're ill, I wouldn't see any harm in that.
To answer your question, though, it depends on how the Bio Odor works. If it blocks certain things, then it can decrease the absorption of the vitamins. Some vitamins/minerals can block the absorption of other vitamins/minerals as well. Looking at the ingredient list, I'd say that one would possibly cancel out the other.