The randomizer has its own set of versions, separated from the game itself. It is possible to change which version of the randomizer you are using, including pre-released versions.
On the home page of the launcher, it will inform you if a new update is available on the top right and you will have the choice of installing it by clicking on the Install Upate button or launching your seed directly and playing on your current version of the randomizer.
Since Version 2.0 of the randomizer, it is also possible to downgrade version by hovering a version patch note on the home page and clicking on the Downgrade button which will appear on the lower right part of the patch note.
In order to update to prerelease version, you have to first enable the developer tools in the settings and enable the Update to prerelease versions option. Once this option is enabled, the prerelease will appear on the home page, just like the stable versions.
When switching from stable to prelease version and vice versa, be careful about the server host set in the developer tools. If playing on a stable version, you should set it as wotw.orirando.com and to dev.wotw.orirando.com if playing on a prerelease version.