i think you are addressing 2 different issues here and here is why:
on our server we also noticed that recently almost any banish adds up to over 100% possible damage. the most obvious when we started to notice was when there was 5 peeps in that particular banish and the 1st had 57% and 2nd placed had 52% ...

that being said, i have also noticed that when the last player goes in and does a lot of damage the total percentage doesnt get updated to some players and it shows the damage that was done from the previous round until you refresh again. i am thinking you may have done the same observation?