Definitely an error in the preparation of the solution.
As for "the solution should be close to neutral", that's true, but if my calculations are right, that is because of the buffering effect of the urea.
We'd gotten as far as 1712.3 moles of NaOH and 1729.8 moles of DDBSA in 2325.6 liters. That gives an excess of 17.5 moles of acid - 17.5/2325.6 = 0.00752M, giving pH ~ 2.
This is where the last piece comes in - urea is a weak base with pKb = 13.8, there is 1193.1 moles of urea added to 2325.6 liters of a 0.00752M strong acid, what is the calculated pH?