What the dealer sells with the tractor is what I'd say usually comes with the Kioti. Mine came with an Interstate battery, in both Kioti's I have owned. (Interstate is the ONLY battery I will use in any of my vehicles, tractor, boat, ATV, etc. I used to be a dealer for them.....)
When you say you 'checked the battery' and it turned out to be 'bad'- what did you do to make the determination the 'original' battery was 'bad'?
If your dealer installed the AC/Delco in the first place they could easily have replaced it under the battery's own warranty. Every manufacturer puts a coded date stamp on their battery's to determine when it was manufactured.
If the tractor sat for a year before you bought it they probably did not maintain the battery properly and it died a premature death.
Anyway, you got lucky for the sound of it and someone took mercy on you. Now you ought to make sure the new battery gets better care and it should last a decent life- assuming it is sized properly, correct cold cranking amps, (CCA), etc.