History is written by the victors, so they say, and Obama famously declared, "I won." So the evidence he sponsored earmarks (which he is publicly speaking against) must be destroyed. Jonathan Allen of CQ Politics reports on the process of hiding the evidence:

Congress will scrub President Obama's name from a list of earmark cosponsors in the $410 billion omnibus spending bill.

The reason: Whether Obama cosponsored the earmark depends on what the definition of earmark is and when an earmark becomes an earmark, according to the Senate Appropriations Committee.

The provision itself is still considered an earmark, and it's staying in the bill (HR 1105) - but it's losing the Obama brand.  ...

Subsequently, Senate Appropriations Committee spokesman Rob Blumenthal said Obama's name would be removed from future versions of the congressional report identifying earmarks and their sponsors.