I cannot understand the way billing cycle gas usage is determined. I would think it is as simple as meter reading at the end of the period minus meter reading at the end of the previous period = equals the usage for the billing period. My latest bill seems to indicate that two billing cycle periods have been used to determine gas usage. This includes meter readings from the previous period that have already been recorded calculated and paid!
Welcome to AGL Neighbourhood!
The meter readings shouldn't be overlapping. Have you had adjustment on your previous bill that has changed your end read?
I'd be happy to check this for you. I'll send you a private message to get your account details from you, so that I can help you further.