visual composer conflict with custom theme

Hey. I'm trying to understand something about the way plugins and themes work together.

I've got a multisite. I'm using 'Share it!' a theme from Themeforest which has it's own visual composer plugin.

However, I would like to install 'X', which is an entirely different theme with it's own visual composer plugin on another site wihtin the multisite.

The issue is that when the Share it! visual composer plugin is activated, it conflicts with any other version of visual composer.

Is there a way to selectively turn on/turn off plugins on a per-site basis?