> I've got it working currently by splitting up the
> resulting mirrors into two separate folders (called
> 1 and 2) but really I would like them to coexist in
> a single folder.  When I tried running the following
> commands without using folders 1 and 2, the second
> call to httrack deleted all of the files downloaded
> by the first call.

HTTrack doesn't really work how it sounds like you want it to.  You are
downloading to a "project" folder and all the files in there belong to that
project, so when another project comes along (your second HTTrack execution)
it finds that all the existing files do not belong.

You could try using "do not purge" options, etc.