Cannot Change Filename (Source And Destination Filenames Are The Same)?

Let's say " 01 - come.aaa" (A space at the beginning) is the file name.I am trying to change it to "01 - come.aaa"(without the space at the beginning).I am coming up with this error: "Source and destination file names are the same".1) Is this fixable? How?2) How can I find all files on my computer (and external drives) with a space at the beginning in the filename (and of course how can I change them with this error coming up)?3) Is it a problem to have a space at the beginning in the filename (These files will be used in Mac and Linux too) ?