The only difference between dragging and dropping and importing the footage is organization. It will optimized the same, create proxies the same etc. The value of importing is that it will create the keywords which will be what ever file you have the original folder in. To be more specific, you have a folder named "Cat Video" You import that folder, not the files in that folder. You just click on the folder and import. In the browser, you will now have a keyword folder ( I don't think FCP calls them folders, but I am going to call it that) called Cat video. If you just open the Cat Folder and grab all the video files and import all the lose files, no keywords will be created. So the point is, it is a great feature for organzation and finding particular files in final cut. If you just drag and drop, again, it will not create Keywords. Now, you can go through all those video clips and assigned keywords to them, but that is time consuming. I hope I explained it well enough for you the difference. Lastly, I dont know why, at least for me, some times, I am unable to drag and drop a video file into Final Cut. I should be able, but it only lets me import. I dont know why. There must be something I am missing when I can't just drag and drop. Hope this helps. Either way, I don't see any way it would duplicate footage. So you don't need to worry about that.
