We report on the dynamics of the periodic collision process occurring between different pulse bound states in a stretched-pulse erbium-doped fiber laser. The acquisition of a large number of second-order correlation traces allows us to reconstruct the dynamics of a single collision event. The measurements clearly demonstrate that, unlike true solitons in the case of integrable systems, the pulses do not fully overlap in the course of a collision. Instead, the collision proceeds through the exchange of bonds between the individual pulses constituting the bound states.