Emulation is the effort to act like someone else. Your emulation of your older brother on the tennis court might create a rivalry between you, as you become a better player.
Emulation comes from the Latin aemulat- meaning "rivaled, equaled," but we usually use emulation in a non-competitive sense, like the emulation of a role model. Having a role model can be useful. Your emulation of that person can help keep you focused toward your goal. It's when that admiration turns into a competitive obsession that emulation becomes a problem. In computing, emulation is the technique used so one machine gets the same results as another.