Wow, OP has just found a simple yet elegant way to double your holdings:

1. Sell your Bitcoins
2. Then withdraw them

After executing this sophisticated strategy you are left with both your original Bitcoin holdings in a wallet and their current fiat value on the exchange. Amazing. Hey, OP, you should've sold your cash-cow-strategy to a few selected individuals under NDA and not publish it for free. Now everyone will do it and crash the price to zero.