measurement problem - In the double slit experiment, what happens when there is more than one observer trying to see which slit the same electron goes through?

From all the demonstrations Iv been able to find of Heisenberg's double slit experiment, whenever an observer tries to "see" which slit an electron passes through it collapses the wave function. My question is what would happen when you have two observers or detectors trying to detect the same electron, will they see the same thing? does the wave function only collapse to one possibility no matter who or what the observer?