The latest release of the Redirect URL to Post WordPress plugin adds another parameter: each_once
With each_once you can prevent that visitors see the same post twice in a series of random posts. Use each_once=rewind to start over again after all posts are done. Use each_once= with a target post/page ID if you want to send your visitors to a post or page after all posts are done.
This feature works only if visitors have cookies enabled.
Hint: If you add the parameter &rutpdebug, you will see a warning if the post IDs wouldn’t fit into a cookie.