I traveled on Mumbai - Madgaon JanShatabdi, that interestingly enough has an RSA with Aurangabad Janshatabdi. However, the rake I had (it was KR), showed the right plates on each coach, except on the end coaches where it had numbers for both JanShatabdis.
In case of the two Rajdhanis, RSA may not be a daily occurence but used when one rake goes for longer maintenance (I assume that happens once a week) than the 8 hours would allow at Mumbai.