Since the original copy remains you can try to run it on two computers.
But some apps do not want you to do that (if the license states the app is to be installed on one computer). Then if the two computers are on the same network you could get a message telling you the app is already open and running on another computer.
Also, many apps have associated files installed in folders other than Applications. In this situation copying just the app from one Applications folder to another on a different computer will not be sufficient for the app to run on the second computer.
But as QuickTimeKirk has already told you, the second is just a copy. So if the legal and other issues are of no concern, you can try it without hurting the original installation.