SerializableObject#copy does a pointer copy for SerializableType Date.

[bradyellison]

SerializeableType#serialize calls moment(rawValue).toDate(). If rawValue is already a data, under certain versions of moment.js (tested with 1.7.0), moment does not create a new Date object.

Any modifications done to the date are reflected in the original date value as well. Example on JSFiddle.

The simplest fix is to simply wrap the call in:

new Date(<date>);