Your-W2-G should be correct. Box 1 is filled in if there are payments of $600 or more if the payment is at least 300 times the wager. Box 7 is entered for additional winnings from identical wagers.
If you only won $3600, you do not want to report it twice. Box 7 is a valid income line. Adding the information in Box 1 would double the income.
According to the IRS, "Winnings from identical wagers (for example, two $2 bets on a particular horse to win the same race) are added together for purposes of the reporting and withholding requirements. Also, winnings from identical wagers that aren't part of the payment for which the Form W-2G is being prepared are added together for purposes of withholding to determine if the total amount of proceeds from identical wagers is more than $5,000."
[From: https://www.irs.gov/pub/irs-pdf/iw2g_17.pdf]
