Two charges on the same day
Usually one of two things. Either your bank is showing a temporary authorisation hold next to the real charge — holds disappear on their own within a few business days — or there are two separate subscriptions, often created with two different email addresses.
Charged when a free trial ended
A free trial converts into a paid subscription automatically at the end of the trial period unless it is cancelled before then. The trial length and the price that follows it are shown at checkout and repeated in your confirmation email. Cancelling before the last day of the trial prevents the charge.
An unexpected renewal
Subscriptions renew automatically for the same period until they are cancelled. Cancelling stops all future renewals — see How do I cancel my subscription?
In any of these cases, write to info@alvinai.studio with the details listed in I don't recognise this charge and we will review the payments on the account.