Looking for Medicaid spending data, I stumbled upon duplicates that seemed to be doubling the State of Connecticut Comptroller's expenditure records.
Props to the comptroller's office for making these expenditures readily available, and to their quick response that it was in fact an error, and that they were working to fix it. I notified them on Friday, July 21, and it was fixed by Wednesday, July 26.
I downloaded the data Friday, July 21 and the erronious files are preserved in this repo in the data/ folder.
Their web interface was reflecting the error, too. Before and after screenshots are in the img/ folder.