SCP Foundation military bio

A gate suddenly opened in the Ginza district of Tokyo, out came soldiers that look like they are from the Roman era. Meanwhile, in another universe, it's 2091. The SCP Foundation has became so advanced that they managed to invent a machine that can travel to different worlds, so they were surprised when another portal suddenly opened on one of their colonies on another world. Beside these two worlds, there is another world where America was recovering from a nuclear war. And in the ruins of Boston a portal suddenly appeared and what looks like Roman legions came out without radiation protection suits and died immediately. How will they react when they meet with each other in another world beside their own?