I received a 1099 C for tax year 2012 and submitted it as income on my 2012 return. Today I receive a 1099 C for the same account and same dollar amount for tax year 2013. On the 2012 1099 C there is no event code listed in box 6 but on the 2013 1099 C there is the letter G in box 6. Am I obligated to report it as income again this year and if not how do I explain to the IRS that I reported it last year?

Thanks!

#1;no; Code G is used to identify cancellation of debt because of a decision or a defined policy of the creditor to discontinue collection activity and cancel the debt. For purposes of this identifiable event, a defined policy includes both a written policy and the creditor's established business practice.Any financial institution that forgives or writes off $600 or more of a debt's principal must send you and the IRS a Form 1099-C at the end of the tax year. These forms are for reporting income, which means that when you file your tax return for the tax year in which your debt was settled or written off, the IRS will make sure that you report the amount on the Form 1099-C as income. Box 6 will be checked if the debt was discharged in bankruptcy.

#2;as mentioned above; you received a corrected form of 1099c. and the creditor may have sent the same copy to irs.
Note; Even if you don't get a Form 1099-C from a creditor, the creditor may very well have submitted one to the IRS. If you haven't listed the income on your tax return and the creditor has provided the information to the IRS, you could get a tax bill or, worse, an audit notice. This could end up costing you more (in IRS interest and penalties) in the long run.