Do not panic. Remain calm. A level head is key in any doppelganger situation. There’s no reason to assume that your doppelganger is harboring nefarious intentions without first considering all the possibilities.
Is it possible that your doppelganger is simply a dead ringer? A good three out of five doppelgangers are nothing more than harmless people who, due to the random nature of genetics, resemble you exactly. If this is the case, perhaps the two of you can come to some sort of mutually beneficial agreement. (For example: Have you any need for an alibi while hiding a body in the woods?)
Does your doppelganger share a birthday or birth place with you? If so, it’s quite possible that the doppelganger is a long-lost twin. Be wary. Twins tend to come in sets of one good and one evil. According to the Twin Department of the University of Virginia School of Sibling Research, double-good or double-evil sets only occur in one out of five cases. Take a good, hard look at yourself. If you are not evil, there’s a very good chance that your doppelganger is. It will probably try to steal your identity. Do not let it do this. Invent code words with friends and family members. Get an identifying tattoo. Have a magnetic strip inserted into your wrist.
Do you and your doppelganger share an exact DNA? You may need to find a genetics laboratory to make certain. Just one fallen eyelash or pint of blood from your doppelganger can help determine if it is a clone. If this is the case, ask yourself these questions: a) Did I leave my DNA lying about unguarded? b) Am I in possession of something of great value that some person or government organization might be trying to get at? c) Am I a forgetful genetics engineer? (If the security guard at the genetics laboratory greets you by name, it’s likely that option c is the case.)
If your doppelganger does turn out to be a clone, what use might you have for it? Are you in need of a new liver, or are you simply interested in exploring parts of your body that aren’t easily accessible without a mirror. Examining your clone can be a useful pathway to greater self-understanding, and it is a rare day when a person can get a very close look at his own anus. However, and I cannot stress this enough, do not, under any circumstances, have sex with your clone. According to research done by The Klemp Institute of Narcissism and Proctology in Prague, examination of the anus fires neurons in the brain that are very similar to those that occur during mating rituals. Or, to dust off a tired old Marcel Proust quote, “The sphincter is the doorway to a passage that leads directly to the heart.” So, though temptations may be high, resist this urge. This can be incredibly psychologically damaging for both you and the clone.
Does your doppelganger speak in outdated or not-fully-grasped slang? Does it sometimes slip into a foreign and violent-sounding tongue that involves gurgles and hisses? Do your doppelganger’s eyes glow red when it is annoyed? If so, your doppelganger is probably an alien shape shifter from another galaxy, or perhaps even another dimension. Find an easy way out of the conversation and leave as soon as possible. Your doppelganger is meaning to eat you. Do not let it do this. Once it has digested you, it will assume your identity and then begin eating your friends and family members, one by one. Once you are to safety, notify your local extraterrestrial policing agency. They won’t believe you at first, but, as the city falls to ruin, they’ll come around. (Please note: There is absolutely no evidence to support recent “bizarro” universe hypotheses. Nine out of ten “bizarro doppelgangers” can be easily explained as mentally retarded twins. See above.)
Does your doppelganger seem slightly older than you? More world-weary? More wise? Do its clothes seem ultra-hip? Have you been tinkering with plans for some sort of time travel machine in your basement? If so, your doppelganger is most likely you. You may engage you in pleasant conversation, perhaps over coffee at the shop around the corner, but steer away from learning sensitive information about your future as it may cause you to blink out of existence. And, again, do not sleep with you, as this can be incredibly psychologically damaging for both you and you.