Based on Born’s statistical interpretation for the normalized wave function, the twin two-photon thought experiment is reexamined from point of view of quantum mechanics. The emphasis is no longer the pair of twin photons itself, but rather a group of photons with common attributes. All the photons have the characteristics of identical energy and angular momentum, but possess same probability in the opposite direction of momentum, that is to say, this is a group of photon collections, which have the same number in the opposite direction of momentum, while all other quantum characteristics are identical. Following the example of the previous procedure dealing with optical two-hole effect by use of quantum mechanics, the total normalized photonic state-vector function that described the twin two-photon thought experiment has been specifically constructed, which does not describe the entangled behavior of the two photons, but the probability of a single photon, and thus deduces the probability distribution of a photon in the space. When the total number of photons satisfies the statistical requirements to form a complete picture, some fringes of light and dark interval will be displayed. On the basis of retrospective historical origins of entanglement, the point of view of quantum mechanics about the twin two-photon thought experiment was reverted. The so-called EPR paradox, and the entangled two-photon state have been re-interpreted, and a new understanding of quantum information has been put forward.