When creating websites, special characters need to be taken into extra consideration. HTML, the markup language used to write webpages, provides its own means of including special, non-"normal" characters. These characters include accent marks, special symbols, and more.
The reason this is necessary is due to the nature of how webpage files are saved. In order to minimize file size and provide the most consistent experience across computers, an encoding is used that maps each character to a binary (numerical) representation. The binary value of each character is stored sequentially in the file; therefore, the more characters your encoding allows, the larger the file becomes - exponentially. (For more info, check out: http://en.wikipedia.org/wiki/Character_encoding)
When a file is saved with the wrong encoding, special characters are represented improperly because the wrong encoding cannot map the character properly. This can be fixed by changing which encoding you use to read the file. The encoding that IMDb saves its files with is apparently different than that which is sent to your browser, so the characters are rendered with garbage.
The reason the character appears okay on the other page is because the person who wrote it understands how HTML works. As I said earlier, HTML provides a way to represent special characters using non-special characters.
For example, to render a heart in HTML, you can type
♥ when writing a webpage. The result looks like ♥, which is clearly a special character. Yet the way I typed it into this document did not require any special characters. This essentially removes the problem of character encodings not matching, because you should never need to type special characters when writing a webpage.
A lot of websites that allow user input, such as Facebook and Twitter, will automatically reformat these characters in HTML so they appear properly when viewed through your web browser. Apparently, IMDb doesn't do this. I would like to note that the page with the character mess-up was submitted by a user, while the other page is an official IMDb page, which was likely written by someone who understood how HTML represents special characters.