[FIX] web: duplicates header in pivot

For report with duplicated named headers, several columns could get
squashed together.

This fix check if a value is a duplicate or not, and if it is a
duplicates postfix an number allowing to differentiate the two headers
(for the human and the javascript).

closes #6722
opw-634771

addons/web/static/src/js/view_pivot.js

@@ -56,6 +56,8 @@ instance.web.PivotView = instance.web.View.extend({
 
         this.last_header_selected = null;
         this.sorted_column = {};
+
+        this.numbering = {};
     },
     start: function () {
         var self = this;
@@ -472,13 +474,22 @@ instance.web.PivotView = instance.web.View.extend({
     },
     sanitize_value: function (value, field) {
         if (value === false) return _t("Undefined");
-        if (value instanceof Array) return value[1];
+        if (value instanceof Array) return this.get_numbered_value(value, field);
         if (field && this.fields[field] && (this.fields[field].type === 'selection')) {
             var selected = _.where(this.fields[field].selection, {0: value})[0];
             return selected ? selected[1] : value;
         }
         return value;
     },
+    get_numbered_value: function(value, field) {
+        var id= value[0];
+        var name= value[1]
+        this.numbering[field] = this.numbering[field] || {};
+        this.numbering[field][name] = this.numbering[field][name] || {};
+        var numbers = this.numbering[field][name];
+        numbers[id] = numbers[id] || _.size(numbers) + 1;
+        return name + (numbers[id] > 1 ? "  (" + numbers[id] + ")" : "");
+    },
     make_header: function (data_pt, root, i, j, parent_header) {
         var attrs = data_pt.attributes,
             value = attrs.value,