Multiple WW windows could be run simultaneously.
You can do this now by making a duplicate copy of the Weather Watcher program folder. Since the settings are stored in the same location, you probably won't be able to do what you are trying to do.
WW had an option to read a local XML file rather than a live file.
I am experimenting with some code that would make this a possibility.
There was a portable version of WW.
This is on the to-do list.