Just to avoid confusion, 'The Higgs Boson' doesn't mean there's only one of them!
Intuitively, it isn't possible for something to be in two places at once - for instance, if you've got your watch on your wrist it's immediately obvious that it's not still sitting on your bedside table. However, once you're talking about subatomic particles common sense breaks down. My understanding of how a particle can be in more than one place at once revolves round a simple equation:
?x?p≥h/2π
At first sight it can look quite daunting, but it's quite simple; the right hand side is constant, and the left hand side basically states that the product of the uncertainty in position (x) and uncertainty in momentum (p) has to be greater than this constant. So while it says nothing about something being in more than one place at once, it explains why it is impossible to know whether a particle (in this case a Higgs Boson) is in one position or another quite exactly, and since any particle can be expressed as a wave (though there's probably not enough space here to go into it in more detail) it can often be useful to consider the particle as a wave that's smeared throughout the region in which the particle probably resides.
Even more interesting, if you look at the uncertainty in the position of, say, your morning cuppa, you'll find that because it has such a large mass, the uncertainty of it's momentum is massive, when compared to the value of h/2π., thus the uncertainty in it's position is vanishingly small. So while you could describe it as being in more than one place at once, the range of possible positions are so close together that for all intents and purposes they're the same.
