different versions of upfront issue theme

Hi
Is it possible to have different variants of the each upfront theme but i dont want to overwrite each version

so i can have the issue upfront theme which I can redesign then an markertpress e-commerce version so i will have a normal website and an ecommerce version of the issue theme.

now how do i save each as a diferent file to uploadso that one does not overwrite the other when i am creating my theme.

Regards