Strange... I'm not familiar with the older version, but on a clean install I don't have any user files in my program folder.
If you think that there's something worth keeping I would rename the one in the program folder to something else like 'topic_old.topx' then move it to your documents folder with the others. You can have multiple files there as long as they don't have the same name. Then you should be able to select and open which ever one you like.