Im adding this post as I keep getting this problem and for those of you who need help like I did this is what fixed my problem.

Basically when I installed ImageGallery and Uploadify I sometimes have an issue where the Pop Up box for uploading new images has two browse buttons overlapping and will then only allow me to choose a single image to be uploaded from my computer.

This was only occurring in image gallery and not Files & Images.

The issue was the 'javascript' folder. Obviously there is a conflict between releases and the versions I have. So if you have the same issue I suggest you update the 'javascript' folder with the files below.

Perhaps this is only an issue for people like me who have older versions which I use as templates for newer sites. Anyway that was the problem. Hope this helps someone.

This is the script that I used.

imagegallery_init.js

// We'll avoid relying on any specific JS framework to keep this open.
window.onload = function() {
	if(gallery = document.getElementById('gallery-list'))
		gallery.className = "gallery-layout loaded";
}

imagegallerymanager_popup.js

(function($) {
$(function() {
	$('.rotate-controls a').click(function() {
		link = $(this).attr('href');
		 $.ajax({
		   url: link,
		   success: function(html){
		   	$('#preview-image img.preview').attr('src', html);
		   }
		
		});
		return false;
	});
});

$().ajaxSend(function(r,s){  
 $(".ajax-loader").slideDown();  
});  
   
$().ajaxStop(function(r,s){  
  $(".ajax-loader").slideUp();  
}); 
})(jQuery);