When the stock split, the only thing that changed is the number of shares was doubled, and your cost basis per share was cut in half. There is no difference between the two. As for the cost basis, since they were non qualified stock options, any bargain element at the time you exercised them should have been added to your income, and included in box 1 of your W-2 for that year. Your basis in the 900 shares of stock would be the amount you paid - $5 /2 = $250 plus the amount added to your income (the bargain element) divided by 900. It doesn't matter whether you enter the sale as one transaction or two.
