Replace exsisting file?

I know Ive asked this before but cant recall.
When you save a new file or program and it asks you if you want to replace the existing sound, does it simple erase the original file and location?

Also, If you don't replace a sound or program, say you have the sounds in a program folder, as well as a main sample storage folder, is it just being viewed from the program folder? Or are there actually double of that file... one in each folder?

Thanks!
Just looking to preserve drive space
And curious.....