Thanks for this confirmation, Doyle. Obviously the entry in the National Archives publication, THE CONFEDERACY is incorrect as to the date, as is the entry in DANFS. I think the error has also been repeated in Silverstone's entry for the PONTCHARTRAIN, in his excellent volume, WARSHIPS OF THE CIVIL WAR NAVIES.
Perhaps the evidence should be passed on to the publishers of DANFS, for correction in future editions.
As to your statement about Hindman wanting to fool the enemy about the PONTCHARTRAIN, I don't think he deliberately made a false entry in his dispatch, but I would assume that he genuinely thought that the PONTCHARTRAIN was on the White River, unless his statement can be taken in a different context. Obviously the MAUREPAS and the PONTCHARTRAIN worked in coordination with each other, and when the MAUREPAS was on the White, then Hindman may have assumed that the PONTCHARTRAIN was with it, as well.