ATENA can not detect if/when some bodies come into contact. However, I think in this case it may be enough to define an interface with 0 tensile strength, which means the interface will only be connected on the areas with compression. Or, you can additionally add a few load steps (prescribed displacements) to separate the two columns, and the interface will only be "re-activated" if it comes back to compression during the load history.
Please note that even if the "reconnection" happens with the columns shifted along the surface, the connection will still bind together nodes which were close in the original undeformed geometry.