Not sure why its overwriting, normally when you double click on a zip file it opens it as if its a folder, allowing you to copy what you want where you do.  On windows I use a program called Total Commander and on Mac I use muCommander both are paneled based file management.  Here is a link to 5 alternates.  muCommander allows you to go in and out of zip/rar etc as if they are just folders.  Some of the others on the list do as well.  It has been awhile so some of the others may be nicer than mu Now why I included the list.

 

http://mac.appstorm.net/roundups/utilities-roundups/5-alternatives-to-the-os-x-finder/

Xfolders was out of date on there.

Xfolders: http://www.kai-heitkamp.de/cms_en/main.php?content=9&module=0

The Disk Order also looks interesting with its multiple tabs like TotalCommander has.

Hope these help.