Avoiding overwriting the original

In Elements 15, in the "Save/Save As" dialogue box, should I always check the "As a Copy" box? Seems as if it's a good idea to do so, with no downside at all.

Also, when saving a file, if I "Save As," as opposed to "Save," and give the file a different name, isn't that also a way of not overwriting the original? In other words, doesn't that accomplish the same thing (not overwriting the original) as checking the "As a Copy" box? Is that an intentional, safety-providing redundancy?