T.co cached?


I am helping a friend who is using a custom app that will take a twitter post and post it to his Facebook wall.
The problem is that the wrong icon is being selected for Facebook when the shortened url t.co/xxxxxxx is used. There seems to be a cache. Does anybody know how to clear it? I know there is the debug tool/lint tool on Facebook to see what the icon should be and it selects the correct icon based on the meta tags when using the actual URL, but not the shortened one above. I test both urls manually, and the twitter t.co/xxxxxx is keeping an old icon. I also tested it by taking out the image from site completely and it still finds it.

How can I clear the twitter cache? It is not a browser issue, we thoroughly tested.
How can I use the actual url which works when posting to twitter.