First of all, you absolutely should reschedule your interviews since you can't have enough energy to do both the same day. Having two interviews is very very risky.
Secondly, rescheduling the interviews is not dangerous at all:
- Interviewers are EMs or Partners who will not even know
- Even if they knew - they don't really care. There is no penalty for that
Third, BCG I guess is a bit easier to reschedule than RB. Also, BCG interviews are tougher. Thus I recommend to reschedule BCG for later and get the interview experience with RB first
Feel free to reschedule