diff --git a/addons/website/static/src/js/widgets/theme.js b/addons/website/static/src/js/widgets/theme.js
index 420f90da04d..355447c86a4 100644
--- a/addons/website/static/src/js/widgets/theme.js
+++ b/addons/website/static/src/js/widgets/theme.js
@@ -332,6 +332,34 @@ var ThemeCustomizeDialog = Dialog.extend({
     _setActive: function () {
         var self = this;
 
+        // First enforce that all input groups have only one element checked as
+        // it is supposed to be (it might not be the case on initialization, for
+        // exemple if we had data-xmlid="A" and data-xmlid="A,B" and if A and B
+        // are active, the 2 related inputs would be checked).
+        var $radioXMLInputs = this.$inputs.filter('[type="radio"][data-xmlid]');
+        var optionNames = _.uniq(_.map($radioXMLInputs, function (option) {
+            return option.name;
+        }));
+        _.each(optionNames, function (optionName) {
+            var $inputs = $radioXMLInputs.filter('[name="' + optionName + '"]:checked');
+            if ($inputs.length > 1) {
+                $inputs.prop('checked', false);
+
+                var maxNbXMLIDs = -1;
+                var $maxInput = null;
+                _.each($inputs, function (input) {
+                    var $input = $(input);
+                    var xmlID = $input.data('xmlid');
+                    var nbXMLIDs = xmlID ? xmlID.split(',').length : 0;
+                    if (nbXMLIDs >= maxNbXMLIDs) {
+                        maxNbXMLIDs = nbXMLIDs;
+                        $maxInput = $input;
+                    }
+                });
+                $maxInput.prop('checked', true);
+            }
+        });
+
         // Look at all options to see if they are enabled or disabled
         var $enable = this.$inputs.filter('[data-xmlid]:checked');