Yes you are correct, files with the same names in the same directories will be over written. I can't honestly think that anyone would want to maliciously over write an existing file but it would be possible. Its also possible for the zip file to include things like web links which add the artists web page link to the Help/Other Web Links menu within Poser. Now whist this is not harmful I take exception to anyone messing with my menus without asking first. So extracting to a temporary folder for inspection and then copying over the Runtime folder with its sub folder and files I'd say would be good practice.