Headscratcher: javascript references lost

I'm sure to some this is obvious.

I have a little sample code that load a record, creates a second reference to the original nlobjRecord, updates the original's value and the second reference gets the updated data - or that is it has a reference to the original (good)

When I reload the original, the second reference does return updated data.

Hard to explain, here is a short code sample and the results:

 //  Load a record and print a field value  var rec = nlapiLoadRecord('customer', '907');  response.writeLine('rec DOB: ' + rec.getFieldValue(ENTITY_FIELDS.DOB));    //  create a second reference to the original field  var rec2 = rec;  rec.setFieldValue(ENTITY_FIELDS.DOB, '9/21/1978');    //  The second reference print the value that was set on the original  response.writeLine('rec2 DOB: ' + rec2.getFieldValue(ENTITY_FIELDS.DOB));    //  reload the original  rec = nlapiLoadRecord('customer', '907');    //  the second reference has stale data, it's not pointing   //  to the rec var any more  response.writeLine('rec2 DOB: ' + rec2.getFieldValue(ENTITY_FIELDS.DOB));