Kodi 19 Matrix, the more stable version of the software, was officially released a few weeks back. The new Kodi 19 Firestick and Android version comes with new fixes, updates, and features for audio playback, video playback, better database and metadata display, improved game playback, and more advanced security measures.
There are, however, limitations on third-party addons and builds that don’t function properly with this new release. This is because of the recent add-on requirements of Python 3 which most developers haven’t met.
It is not possible to install two different versions of the same Kodi on the same device but there is a Kodi 19 Fork called Nodi 18.0 which you can install alongside Kodi 19. This brings to you the best of both worlds.
You can still use your Kodi 18.9 with your favorite add-ons that are incompatible with Kodi 19 and use Kodi 19 with the addons that are compatible with it.