I've got a theory.
When two people spend an extraordinary amount of time together, inevitably they begin to have a certain type of connection. Obviously, I'm not talking about a romantic relationship or connection of the same sort. What I'm trying to say is that any two people in the world can have such a connection of alikeness that they don't even notice it anymore when they dress alike, say the same thing, think the same thing. Because of this connection, they also being to feel the same things at about the same time, or with a minor delay, so that whatever happens to one person will inevitably happen to the other in some way, shape, or form. Let me give you two examples to back this up:
1. My two managers at work have been working together for upwards of 7 years. Every time that I show up to work, I always see them together. Now, granted, a logical person would reason that they are merely doing their managerial duties of making sure that the store isn't taken for everything inside, but I hold differently. They dress the same, oftentimes say the same thing at the same time, and have very similar personalities. There was even a day when they were both not at the store because both of their wives were ill, and they had to take care of them. Proof: bonded people have similar things happen to them at or around the same time.
2. Personal example: my best friend and I have known each other going on 2 years. We tell each other everything about our lives, have met each other's families, and take the same classes. Its not that we spend every waking moment together, absolutely not, we have our own lives. However, the time we do spend together is chock-full of information and companionship. That being said, she and I have been known to dress exactly the same on the same day, and we've even had an instance involving other people happen around the same time.
During Hurricane Gustav, she went off to Pensacola and met a guy, hung out with him the whole week, and began to develop something there. I, on a similar level, stayed in town and was with my friend the whole week, basically doing the same thing as my friend. Proof: due to our similar nature as friends and our situations, we both ended up in relationships of sorts after a horrific even such as Gustav.
Now, I'm not saying that this happens to every set of friends or coworkers who happen to be good friends. "Good friends" is a term that varies depending on the level of trust between the two people involved. Also, this is not a "puppet master" kind of theory. Sharing something as complex as a friendship or a working relationship develops this trust-bond which connects you to the other person in a way that not many people understand. I, for one, am still perplexed every time my friend and I dress the same without even planning it, or without even seeing each other for days beforehand. Maybe its kind of like the twin theory. The one that claims that a set of twins, triplets, etc., can feel what the other is feeling, though they may be miles apart. My theory may not involve DNA, but it certainly lies along the same lines and plane that the twin theory holds. Who's to say it isn't true?