The processes of collective spontaneous decay of time-dependent quantum systems and the formation of two photons as a wave packets are of great interest to quantum optics [1]. A theory that describes the spontaneous decay of two hydrogen-like atoms on time scales that are small or large compared to the reciprocal photon emission frequency is developed. On short time scales the spontaneous decay rate is found to tend in an oscillatory manner to the exponential law of spontaneous decay. The process of energy exchange in time and space between two radiators placed at distance “d” is discussed. The behavior of non-locality of electromagnetic field in the process of spontaneous emission is observed. This effect gives us non-causality terms in the exchange integrals between these radiators. A great attention is devoted to the process of interaction of two excited radiators with the vacuum fluctuations of the electromagnetic field at initial stage and the transition to the quasi-exponential decay over long time compared to the reciprocal photon emission frequency ω-1.