Re: Two teachers...
It sounds like a fair amount of folks have had bad experiences with training with more than one sensei. I have only had one aikido sensei. That being said I have trained with other senseis and currently train in other martial arts. In today's society everyone seems to be of the attitude that they owe nothing to their sensei. Well, all that aside I think it is important to ask permission from your sensei and when/if he/she gives permission then you also have to get permission from the other sensei. Just a thought.