I'm pretty sure it used to be possible to have two separate Firefox Portable instances (Different folders with different profiles in them) and use them simultaneously with AllowMultipleInstances=true in the settings file. This seems to not work any more. Is there another option to have two separate instances of FF portable and having them run simultaneously?
A few options here:
* If you want to run multiple profiles: https://portableapps.com/support/firefox_portable#second_profile
* I believe it's also possible just run Firefox and Firefox ESR together without additional configuration.
* You can also open the file FirefoxPortable\Other\Source\FirefoxPortable.ini in a text editor and change "AllowMultipleInstances" to "true" and then save changes.
Moderator at portablefreeware.com