thinking on it, there are two good ways for this resurrection storyline to play out: either Fukubei faked his death a second time, or #13 is pretending to be Fukubei somehow and is taking on the mantle of "Friend". Both seem pretty realistic, it all just matters in the execution. I prefer the second possibility, since it means they played the death straight the first time round, but it does mean that Friend didn't expect Yamane to have a gun and shoot him, which doesn't quite fit with his pattern of psychological manipulation and information imbalance.