Good lord, the possibilities for practical jokes (assuming this a secret opportunity available only to me, and not to everyone in the general populace – these Writer's Block questions tend to be vague, ambiguous, and/or just plain downright stupid) are endless. Having the same knowledge, personality, and sense of humor, there are all sorts of things we'd want to do together. However, I think I would definitely grate on my nerves after a while if we spent too much time together – so we'd probably work up a system where we alternated going to work and staying home, and splitting up other tasks and errands. Much like Michael Keaton in Multiplicity, however, we might have some serious issues about sharing where my wife was concerned.
If it were possible to clone a same-age version of yourself, do you think the two of you would be friends? Do you think you'd enjoy each other's company or find the similar point of view boring?