The paper contains an analysis of unsteady phenomena resulting from the interference of the wake flow around the system of sharp-edged bluff-bodies in a uniform oncoming stream. The configuration of two parallel square cross-section prismatic bodies, arranged in a tandem is considered for the 2D case. The program of the study consists of wind-tunnel experiments and numerical simulation performed with the use of phase-averaged form of k-epsilon turbulence model in a RNG version. The original contribution of the paper is the recognition of dynamic properties of vortex structures around interfering bluff-bodies in a tandem arrangement. The numerical simulation provided necessary data to conclude that different flow regimes around interfering bodies are due to the interaction between the separated shear layer from the first obstacle and the reattachment and impingement pattern on the faces of downstream body. The obtained results revealed that time characteristics both of the velocity and pressure field can be grouped in separate classes based on the body spacing, according to observed flow regimes (single-body, bi-stable, critical, quasi-isolated).