Does the duplicate folder remain after a long time, or is it just immediately after the renaming? I have seen something similar to this on FreeNAS between the time of the renaming and the delay before the CIFS share is re-synchronized completely.
5 steps
1. Buy one of these: http://www.amazon.com/16-Port-Serialata-Raid-Ctlr/dp/B000EZUERU
2. Setup Raid 0.
3. Get screenshot.
4. Sell drives and return raid controller with Prime shipping.
5. Post screenshot on [H] forum.