I agree with this question only because on occasion I go over to a friends house & we both play the apps & level off each other while there. Her husband also plays & we all fight each other. Doing this all from the same IP address would appear that 1 person is using multiple accounts. Granted we don't all have the same name & we don't do this but once every few months when the opportunity arises but it does happen.
Also, some people may be using another family members account to play a second account. I know of a couple people that do this especially if their child, sibling or parent allows them to if they don't play the app. So technically, they aren't using a duplicate account of their own. They are playing 2 different accounts themselves and more than likely having the same name. I'm not saying this is right, I'm saying it happens & it's not against the rules to do so.
I also want to point out that in the Terms for Kano it specifically states:
All KANO user profiles, character actions and content in or on the chat boxes and message boards are created by our users and not by KANO. If you post distasteful, insulting, sexually explicit, racially disparaging, religiously disparaging or other inappropriate content, KANO reserves the right (but not the obligation) to delete it from the Site without notice and to freeze or close your account.....
You can access the rest of the sentence & terms by scrolling to the very bottom of the app & clicking on TERMS. Kano does what it can to keep up on bot usage, cheating etc. however as per the terms, they are under no obligation to start deleting or freezing accounts. If an action is made against someone they will certainly never reveal that information to the general public or anyone else asking. As per the comment below from Eric, if you suspect someone is using multiple accounts contact that social network as they do have better tools to see if someone has duplicate or fake accounts . Once an account is removed from from either social network they can no longer access any app.