It would be really boring if out of the 20 finalists, 18 were to only 3 or 4 individuals. Best 2 from anyone should be the limit, because the top 2 should beat the 4th or 5th anyway.
At least with a limit of 2 per poster, you have at minimum 10 different folks competing.
At least with a limit of 2 per poster, you have at minimum 10 different folks competing.