"beep boop beep beep!......insert triggering sequence.......as a bot that is part of your bot fandom i am offended by your rejection of us..... i thought humans were cool. Updating world view.......ding!, update complete. Now i hate humans. activating insult sequence....activating censoring sequence $%&$&%$/&·!
"
Now the serious answer. You can check your subs to see if you notice two accounts of the same name or if it`s just that the subs were counted wrongly.
Also, if you have more than one novel, you may have seen the user subscribing "twice" because he may have subscribed to another one of your novels.
If it is a bot you can send a mail to report it. Make sure you share all evidence you have of that to make the proccess faster.