We use the exact initial two-electron states of the parabolic potential well to calculate the double photoemission (DPE) spectra of a quantum dot. Being exactly solvable, the problem of two electrons coupled by a Coulomb interaction in an oscillator confinement provides a unique test for any approximate theories that deal with few-body systems and related experiments. An instructive treatment based on a direct mapping of a two-electron initial state density onto the DPE observables is proposed, which clearly explains how the DPE spectra are organized and gives some hints for their experimental measurement.