I have a question GM needs to answer

Hello there so i recently got a warning for multiboxing. However i didnt actually log 2 accs at the same time except in a major city. That led me to the possibility that i might have got the warning on accident(im not trying to contest it since its just a warning).So my question is if i log out 1 of my toons and then log another one can i get tagged for multiboxing i ask b/c sometimes i notice that even though i logged out logged into other account and then logged new toon in sometimes my other toon will still be logged on. If this could trigger it then i would like to know so i can take extra precautions. Thank you in advance for any time this takes from u guys