That definitely happens to me. Also, my mind occasionally has the annoying instinct of repeating in my head what I just said or a conversation that just happened. When I was little my parents would notice me subconsciously repeating things to myself. Although that's probably just me being strange and slightly OCD...
I have an INTJ friend who does this, the repetition, I guess when he was younger he did it out loud, so he would say things twice.
I on the other hand have a dialogue/monologue/musical(more like a symphony)
I almost always have a song playing in my head or at the very least out of my head, when it's outside it lets me focus on other things but I use it to give my life rhythm, otherwise I'm a completely scatterbrained mess.
As far as dialogue goes I keep the voices of the people I remember in my head, like my bestest friends from the past, the first girl who gave me a compliment, the person who stole my pokemon cards in first grade, various people who made an impact on my developing form, etc. I keep them to remind me of who I am and why I do what I do(or don't do). Most of them tend to keep in the background, but come out in the winter when I'm no longer very good at keeping my nervousness and mild paranoia at bay.
I'm currently holding a conversation with an old friend who I managed to hurt and various mutual friends trying to figure out the best way to mend things.
EDIT: Don't feel bad about opening old threads, I don't think they would keep them around if we weren't aloud to bring them up again