Login as user

In moodle I can login any user (i.e.) and act like the owner of that username. Is this possible w/ D7? My purpose is to transfer the post of a user who submitted into the wrong content type.

Ex. Some of my member submit their source code in the blog section instead of submitting it in the source code content type. So what I want to do is login to that username and transfer his/her post manually to source code content type. I know I can change the author when I create a node but the problem is I use specific folder for every user that upload their file on their own folder as their username. So if I upload the file when login as admin even if I change the "Authored by" the file will still be saved on my folder and not to the author of the file.