Running Application From External Hardrive on a mac I have copied my application to external my hard drive but when I run it it copies the application to the application folder on the mac and then runs.
Have you considered moving the copy of the application from your /Applications folder to maybe a temporary folder (or delete it, if you have a copy of that application already on your external HD) to see if that resolves the issue?

Also, can I ask what application it is and what version of Mac OS you're running?