I assume you have added two new fields which are of type char.
Now in DSO you added them in data fields and reload the same data..No issues your KF will get overwritten and the data will be filled in newly appended fields.
In cube you added the two new chars..As in cube each char acts a primary field.
Lets take it this way.
You already have data with the old records.
New data will be loaded and create new combination of records based on newly added fields.
So i feel you need to drop the data and reload in cube.
Regards,
AL