It's often been said that Hollywood has certain "types": the beautiful girl next door, the suave leading man, the femme fatale, the bad boy, etc. Given the show business predilection for specific looks and attributes, it's only natural there will be famous people who look identical, or close to it. Even stars at the height of their fame, popularity, and exposure have experienced being mistaken for another notable personality.
There are a few reasons behind this phenomenon; the biggest being looks. In an industry overrun with a specific idea of what makes a celebrity, obviously, some frequently mixed-up stars are going to resemble one another. Another reason is image; when two celebs fit those character types mentioned above, it can be easy to confuse them for each another. And in some cases, famous people who are always mixed up can share nothing more than a similar name.
Whatever the reasons, celebs who always get mistaken for each other usually take it in stride and realize, as we do, that the similarities can be striking.