While some e-mail programs do have an option to include/exclude yourself from "reply all", I don't think Aquamail has one. At least, I don't remember seeing it, and couldn't find it upon a quick look.
However, I just checked: Aquamail doesn't include my own address in "Reply All".
Check if the way your own e-mail account in Aquamail (and any identities if configured) is (are) set (with regard to the address) exactly to the way as it appears in the address in question.
In my experience, if Aquamail can match any of the addresses to one of "yours", then it will not include that address in "reply all". If there is a difference (no matter how minor), it will assume that it is not your address, and add it to the list of the recepients.