Investigators established that farming equipment was being used in the vicinity of fields immediately before the fires were first reported.
The first fire started in a field near Racecourse Lane at about 13:27 BST on 13 August, while a second began shortly afterwards in a field near Quarry Park Road.
Chief Fire Officer Simon Tuhill said so many people had been affected the service wanted to confirm both fires were not started deliberately. They were accidental, he said.
He added: "I know that many are still struggling to comprehend the scale of damage and personal loss.
"I'm also acutely aware that this information will not bring those back homes, livelihoods or cherished memories."
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