You simply have to generate a sequence of unique filenames to save to. Something like this:
outfile = fullfile(outfolder, sprintf('%s-coba-%03d.%s',basename,n,ext]);
That way you'll generate filenames of the type: basename-coba-001.ext - I replaced the whitespaces in the filename with '-', because I prefer to have dashes instead, you can switch back. The %03d is just to give you zero-padded numbers incrementing with your loop-variable n.