Tuesday 03 May 2011 5:29:51 am

You shouldn't lose the original versions. When creating an Alias, the original is untouched and a new version is created according to the alias settings. The images you see in frontend and full view in the admin are also alias versions.

To verify, in firefox, right click on the image and click on Copy Image Location, the URL will be ending with '_aliasname.jpg' remove '_aliasname' and you should have the URL to the original image