So did it work? I see that you put destroy call in window beforeunload event, this should not be necessary. If you are already unloading window/page, then it will already be destoyed. What I meant was, if you are manually removing the component's DIV element when you are switching tabs, you should not do that and call destroy instead.
> We have two ADMs on a page both loading in the same div and replacing the previous.
So if you are replacing the previous in JS (or Jquery), instead of deleting the previous component's DIV element, call destroy for that component ID.
By the way it's not
$('fileManager').destroy();it's
fileManager.destroy();
fileManager or fileManager2 are defined in JS according to the FileManager.Id. The method you used is for jQuery components and it's not related to FileManager.