I had a question regarding a sale of ESPP. My friend has sold ESPP and the income is shown in the W2, however the company has also included the capital gain in the W2 because he had received the amount in his paycheck. As far as we know, the capital gain should be reported on Schedule D and not on your W2. How would we report the ESPP sale here? If you show the capital gain as part of W2 and also on Schedule D then wouldn't that be showing the gain twice? Could it be possible that the company made a mistake?

Thank you