Rb's EXP

Hello. What happened with the experience from the RB? At the party on 65 rb i had 2 characters lvl 66, first received 30% of the experience, second 70% exp. At 70 lvl rb my characters lvl 66 received 30% experience, another 68 lvl characher got 1 lvl . On the other rb lvl 70, the first 67 character received 20% of the experience, the second 45%. WTF ????