If you give the same seminar to several different groups of students, do you never feel temporarily unsure of what you have said to one group or the other? I know I do. (The worst part of it is when I can't remember whether I've told a particular joke to a group or not - actually, no, the worst part of it is when I realise I've told the same joke twice to the same group...) In RL I talk to very few people (I could number them on the fingers of one hand even if I lost a couple of fingers) about my personal life and problems. I can still sometimes be a little confused regarding whom I've told what, and who said what. I'm sure I'd be confused if I saw more than one T.