Talk:Endless Defense/@comment-80.187.103.181-20130611133114/@comment-92.238.111.176-20130616174713

Technically it's not a bug, the system used to pick out your 'random' leaving prize is just not very good. It sets a value on wave 5, and then adds a specific integer(number) on wave 10, and this integer is used in picking all further 'random' mod rewards. That means it is possible for the drop table to repeatedly pick the same mod over and over. A more... in depth explanation is on the reddit:

http://www.reddit.com/r/Warframe/comments/1fl18h/defense_mission_rewards_and_scaling/