Be careful with allowing a page to render using the same method as Stack overflow.
http://stackoverflow.com/questions/820493/random-text-can-cause-problems
Black hats can this to cause duplicate content penalty for long tail competitors (trust me).
Here are two things you can do to protect yourself from this.
- HTTP 301 redirect any inbound display url that matches your ID but doesn’t match the text to the correct text.
Example:
http://stackoverflow.com/questions/820493/random-text-can-cause-problems
301 ->
http://stackoverflow.com/questions/820493/can-an-seo-friendly-url-contain-a-unique-id
- Use canonical URLs.
<link rel="canonical"
href="http://stackoverflow.com/questions/820493/can-an-seo-friendly-url-contain-a-unique-id"
/>