How can I run two instances of WhatsApp on a Mac?
Simply open terminal and run this command:

/Applications/WhatsApp.app/Contents/MacOS/WhatsApp /secondary


Two remarks:


The app seems to crash if you subsequently close the terminal (even if you use &amp;) so keep your terminal open. Sudo may solve this (as seen here) but I didn't really try.
If anyone knows how to make it launch from Spotlight, please share your ideas. I would love to improve on this method and make it easier to use.