[BUG] "Multiple paths" checker should make sure paths aren't equal before warning user

e.g.

$ astra setup
Warning:  Multiple astra home folders were detected at the following locations:
Warning:   - /home/runner/.astra (default location)
Warning:  
Warning:   - /home/runner/.astra (custom path set via environment variable)
Warning:  
Warning:  Please either:
Warning:   - remove or migrate the lower priority files/folders (custom > xdg > default/home)
Warning:   - set 'ASTRA_IGNORE_MULTIPLE_PATHS=true' or use the '--ignore-multiple-paths' flag with 'astra shellenv' to suppress this warning