how to save alternate versions of Xcode projects

I'm just getting started with Xcode and notice there's no "save as" command. I'd like to have several different versions of a project, each differing by about 20% of the code, without having to retype, or fastidiously copy/pasting all the files. I can't seem to accomplish the same thing with the "duplicate" command.

I notice "save as" has been asked about here before but in those cases it seems the eventual solution for the op served a slightly different purpose than what I'd like to do.