You don’t need to deactivate the regular Photoshop. You can activate Pixnub on both the beta and the normal PS release. Since it is the same computer, the activation server will know that and only count it as 1 computer. Same thing if you installed CC 2022 along side CC 2023. You need to activate both. However, the license server still only counts it as one computer.
I wish there was a way to have 1 activation automatically activate all of the other PS installs. However, this isn’t possible the way Adobe designed the new Plugins system. However, you can activate Pixnub on as many PS installs on the same computer as you want without running into issues.