Basically using the Popups Module causes the AD Gallery JS Drupal behavior to be called/rebuilt whenever a popup is loaded/AJAX responded. I haven't looked into why the Popups Module's JS is calling the behavior as Popups is no longer being maintained. You'd be right to say that this is probably a Popups issue, but it might be a good idea to just avoid the regeneration of AD Gallery entirely in preparation for why this is even possible.

Here's what I did to resolve:

		if(!Drupal.settings.ad_gallery_built) Drupal.settings.ad_gallery_built = true; else return;

In adding this to line 2 of ad_gallery.js, will stop the ad_gallery behavior from being called more than once.