The holiday shopping season begins Friday with a blitz of early morning specials. For some merchants, though, it’s practically over already. At warehouses operated by Liquidity Services Inc., a leading online auction company for surplus goods, there are rows and rows of pallets of offloaded merchandise ranging from jewelry to consumer electronics. At the company’s Liquidation.com, which auctions surplus goods offered by stores and manufacturers to dollar stores and small businesses that sell on eBay, the number of auctions scheduled for the Thanksgiving weekend has soared to 2,100 – eight times more than last Thanksgiving, said chief executive Bill Angrick. In other words, what normally happens after Christmas is taking place this weekend, he said.