JucePlugin_PluginCode / setUniqueID

I am currently working on a VST3 adapter that wraps my existing vst2.4 plugins.
I am not sure if it smart to use the same pluginID /setUniqueID (JucePlugin_PluginCode) for the VST3 adapter as the the vst2.4 version.
If possible people should continue to use the native 2.4 version instead of VST3. I think some hosts (Cubase?) replace the vst2.4 version automatically with VST3 if this one exists.

  1. What are the pros/cons of using the different/same JucePlugin_PluginCode for VST3/VST2.4 ?

  2. Is there a possibility to set the JucePlugin_PluginCode during runtime on PC?