André,
The Like button is intended for unique URLs. That URL is what will be shared in Facebook for a user's friends to click on to visit the page to see what the user Like'd. If you don't have an individual URL for each picture, you can 'fake' a unique URL for each poster like the following:
{JFBCLike href=http://yoursite.com/link-to-poster-page?poster1}
{JFBCLike href=http://yoursite.com/link-to-poster-page?poster2}
{JFBCLike href=http://yoursite.com/link-to-poster-page?poster3}
That will create a unique count for each Like button, but when clicked by a user, would bring the user to the poster listing page.
I hope that makes sense and helps, but if you need anything else, just let me know.
Thanks,
Alex