I'm not sure it proves dualism one way or the other, but then I don't know much about the theory of dualism. It seems to me that it is an unnecessary complication and that mind is very obviously a product of matter, but I digress...
In the Copenhagen interpretation, it is always the observation that collapses the wave function. This leads to some very strange conclusions, for instance, if an observer is in the room watching the equipment and his colleague is in another room, then to the observer the experiment has completed and the outcome is known, but to his colleague the experiment and the observer are still in a superimposed state, until he opens the door and asks what the outcome was.
This is an example of the silliness that comes out of the Copenhagen interpretation when extended to the human scale, as exemplified by Schrodinger's famous cat.
The alternative is the many-worlds interpretation. Here the decision is made at the detector, but the experiment creates multiple versions of the universe in which different outcomes of the experiment have happened.
What the many worlds interpretation says about consciousness is that it is not a single strand running through time. Instead it is an infinitely branching tree; there are an infinite number of copies of me all experiencing different versions of reality, and new ones are being created all the time.
The many worlds view clearly drives a coach and horses through concepts like the soul and sin, so I think that those with even a slightly religious bent have a hard time accepting it.
Other people have a problem with the idea of continuous creation of new universes. I prefer to think of it as the discovery of pre-existing possibilities. What we experience as time then is a random walk through the space of all possible states of the universe.