Alright, I have taken a look at the games and the errors made.
Here are my findings:
1) 14 people were invited to join Round 5.
2) 4 players joined both games.
3) The PM invite did not contain specific joining instructions.
4) The PM invite did contain a link to the tournament thread.
5) The PM invite also did contain a reference to the number of spots created in each of the games.
6) The previous rounds have all been one game per round.
7) Despite receiving numerous PMs from players left out, and several postings in this thread, none has noticed they joined too many games.

Additionally, assuming players generally joined games all at once, it is apparent that most of the players in the games once did understand the rules.
9) Additionally, many of the PMs received about the issue contained words to the effect of "I cannot join because some players joined too many games."
10) Therefore, it is my conclusion that the rules were understandable to the average player and fully enforceable
JUDGMENT:
Players joined both games are eliminated this round, as per rules page:
Eliminations:
One person will be eliminated from each game.
They will either be the target killed,
Or anyone who kills the wrong target.
Anyone who doesn't join will also be eliminated.
Anyone who joins more than ONE game per round is eliminated.