Use the most easily recognized name. An article should refer to the most common name of a porn star or the most common term for a thing.
Add redirects. A redirect should be created for articles that may reasonably be found under two or more names (such as different spellings or former names).
Capitalization. Capitalize all words of a film title or porn star, but avoid this for articles that are not about proper nouns.
If the name you want is taken: use that name plus something in parenthesis to differentiate it from the other page. For example, if there is already a movie called "Desire" and you want to create a page for a porn star named Desire, you could name your page "Desire (porn star)". Or if there is already a porn star by that name, you could call your page "Desire (II)".