is it possible to use the eap plugin with my 2018.3.3 preview and the stable plugin with my 2018.3.2 idea? it seems that they both use

IntelliJIdea2018.3

as config directory

You can set a custom directory for the second IDEA: https://intellij-support.jetbrains.com/hc/en-us/articles/207240985-Changing-IDE-default-directories-used-for-config-plugins-and-caches-storage