Not to boast, but I know how the Museum of Modern Art acquired that painting, and it's a singular narrative. No other art work ever came into its collections with this tale to tell.
Back in the 1960s, when Seattle collectors Bagley and Virginia Wright owned it, it was frequently on loan to museums. One day a crate showed up at the Wrights, and Bagley, reasonably enough, pried it open. Finding the Rauschenberg, he removed it and carried the crate to the curb for the trash collectors.
A few days later, Virginia asked Bagley if he'd seen her Lichtenstein. He hadn't. She called the museum and learned the crate held not just the Rauschenberg but also the Lichtenstein.
She stopped speaking to Bagley. He said later he had never seen her that mad. In response, he launched a desperate search, finding his target in the house of the trash collector. The man had saved the crate, found the Lichtenstein and folded it for later use, possibly as a table top.
Lichtenstein said he'd repair it if the Wrights donated it to MOMA. Bagley said he has never under any circumstances opened another crate with art in it.