Looks like Walmart will be the generous one covering the losses.
Wal-Mart, Xerox blame each other for Louisiana shopping gone wild - chicagotribune.com
He said emergency procedures in place with Xerox allow retailers to call a phone number and receive authorization for purchases any time the EBT system is down. "Some retailers chose not to follow the process," he said. "Those businesses are only being reimbursed for the (maximum) amounts on individual cards," he said.
Williams said that amounts transacted above the cards' available balances were returned to Wal-Mart marked "as insufficient funds."