I don’t think there is a good answer to this. You could detect that a different version is activated and then deactivate it, but this would not work of the other version was also installed in a plugin, or in the theme. Even if this would work there is still the problem of the two versions not being completely compatible. This is one of the main reasons that I do not build ACF into the plugins that I create that require ACF and instead say that ACF Pro is a requirement of using my plugin. Some of my plugins cannot even be activated if ACF Pro is not active. There have been cases where I had to completely rework a plugin for sites that use themes that include ACF4 because there wasn’t any way to deactivate the requirement for ACF4. There have also been cases where I have refused a project because it was impossible to make the site compatible with my needs.
Sorry for the long non-answer answer.
