Don't validate twice in

backbone.js

@@ -455,11 +455,14 @@
 
       options = _.extend({validate: true}, options);
 
-      // If we're not waiting and attributes exist, save acts as `set(attr).save(null, opts)`.
-      if (attrs && !options.wait && !this.set(attrs, options)) return false;
-
-      // Do not persist invalid models.
-      if (!this._validate(attrs, options)) return false;
+      // If we're not waiting and attributes exist, save acts as
+      // `set(attr).save(null, opts)` with validation. Otherwise, check if
+      // the model will be valid when the attributes, if any, are set.
+      if (attrs && !options.wait) {
+        if (!this.set(attrs, options)) return false;
+      } else {
+        if (!this._validate(attrs, options)) return false;
+      }
 
       // Set temporary attributes if `{wait: true}`.
       if (attrs && options.wait) {

test/model.js

@@ -712,6 +712,15 @@ $(document).ready(function() {
     equal(model.get('a'), void 0);
   });
 
+  test("save doesn't validate twice", function () {
+    var model = new Backbone.Model();
+    var times = 0;
+    model.sync = function () {};
+    model.validate = function () { ++times; }
+    model.save({});
+    equal(times, 1);
+  });
+
   test("`hasChanged` for falsey keys", 2, function() {
     var model = new Backbone.Model();
     model.set({x: true}, {silent: true});