City health officials last month accused Frank Luo of altering the 22-year-old horse's ID number so that he could work under a younger horse's license. The older horse was supposed to be resting at a Pennsylvania farm.
An investigation was underway when Luo sold both horses, hindering the city's effort to sort things out.
Luo denies the allegations. He said Friday that the horses simply look alike and a city veterinarian got "confused."
The Department of Consumer Affairs says it is investigating.
Mayor Bill de Blasio has vowed to ban the carriages, calling them inhumane.