I'm not a Bond fan, and haven't seen Casino Royale (2006).
But I've seen once Casino Royale (1967), and when the 2006 movie came about, I thought: this same-title business could be confusing. But then again I looked at a list of many american movies, and I realized that two or even more movies with the same title is not that uncommon of an event. For instance, three comedies like "Duck Soup" with Laurel and Hardy (1927, short), "Duck Soup" with the Marx Bros. (1933, feature), and "Duck Soup" with Edgar Kennedy (1942, short).
Anyway, the pointless question is: to the people who have seen both "Casino Royale" 's, if you had to choose between one of them, which one would you choose?