The Wall Street Journal identifies a single bidder who was buying in bulk at the Polaroid sale:

A bidding war developed over two of Mr. Warhol’s 1979 self-portraits, each priced between $10,000 and $15,000. The first of the 20-by-24-inch images, “Self-Portrait (Grimace),” sold for $146,500 to a single telephone bidder, setting a new record for the artist’s photography at auction. That record was promptly broken with the subsequent lot, “Self-Portrait (Eyes Closed),” which enticed more than seven bidders before going to the same buyer for $254,000.

The telephone bidder, identified only as L0153, bought so many of the sale’s works – including pieces by Mr. Adams, William Wegman and Lucas Samaras, among others – that sale attendees began to whisper, and later chuckle, each time the auctioneer acknowledged the specialist bidding on paddle LO153’s behalf. Sotheby’s declined to identify the buyer.

Sotheby’s Photo Sales Take in $12.5 Million (Wall Street Journal)