Internally, duplicate keys are maintained

[fabien]

There's a bug in Dirty.prototype.set() where keys are pushed onto _keys, even though they have already been set. This is immediately noticeable when iterating using forEach.

The fix is very simple:

if (!this._keys[key]) { // FAIL - _keys is an Array
  this._keys.push(key);
}

should of course be:

if (this._keys.indexOf(key) === -1) { // FIXED    
  this._keys.push(key);
}

[dylang]

Having this problem too. Thought I was going crazy until I switched to an older version of Dirty. Every set results in another key being created.

[milesw]

Same thing happening here. Not crazy after all...

[danmilon]

Affected also!