Error Opening Emulator emulator: ERROR: Running multiple emulators with the same AVD is an experimental feature. code example
Example: Running multiple emulators with the same AVD is an experimental feature
Removing the .lock files did the trick for me. Find the avd and remove the lock files. In a Mac .android/avd/'NAMEOFAVD.avd directory . The files I removed were hardware-qemu.ini.lock and multiinstance.lock.