If by a "second copy" you mean another 8949 page with a different sales category, you just enter a transaction with different category and the program will create one. For example, if you enter a short-term transaction where the basis is reported to the IRS, TurboTax creates a page 1 with category A checked. If you enter another short term transaction for which you did not receive a Form 1099-B, the program will create another Form 8949 page 1, with category C checked.