Staying at the hotel now under two rooms as a platinum. I was told that only two guests (out of a total of 4 in the two rooms) are allowed access to the concierge lounge and have breakfast. Is this the official rule?
Yes, it is only for main member + 1.
Earlier this year, when it was a Gold benefit, me and my wife both had the status, so we booked the 2 rooms separately, and got the lounge access for 4 guests. If you book 2 rooms under one account, you still only get 2 passes to the lounge.