Nope. In the sixth book, prof Trelawney tries entering while Malfoy is already inside.
The Room of Requirement,' repeated Harry. 'Were you try-ing to get in there?'
'I - well - I didn't know students knew about -'
'Not all of them do,' said Harry. 'But what happened? You screamed ... it sounded as though you were hurt...'
'I - well,' said Professor Trelawney, drawing her shawls around her defensively and staring down at him with her vastly magnified eyes. 'I wished to - ah - deposit certain – um - personal items in the Room ...' And she muttered something about 'nasty accusations'.
'Right,' said Harry, glancing down at the sherry bottles. 'But you couldn't get in and hide them?'
He found this very odd; the Room had opened for him, after all, when he had wanted to hide the Half-Blood Prince's book.
'Oh, I got in all right,' said Professor Trelawney, glaring at the wall. 'But there was somebody already in there.'
'Somebody in -? Who?' demanded Harry. 'Who was in there?'
' I have no idea,' said Professor Trelawney, looking slightly taken aback at the urgency in Harry's voice. 'I walked into the Room and I heard a voice, which has never happened before in all my years of hiding - of using the Room, I mean.'
Later on, she says
Everything went pitch black and the next thing I knew, I was being hurled headfirst out of the Room!'
So basically, she tried entering the room when Malfoy was already in it, and thus entered the same room that Malfoy was in.
Another scenario is in the Deathly hallows, where Harry needs to empty the room to search for the diadem:
He knew that the room would not be able to transform while there were still users inside it.
“Ginny,” said Harry, “I’m sorry, but we need you to leave too. Just for a bit. Then you can come back in.”
Ginny looked simply delighted to leave her sanctuary.
“And then you can come back in!” he shouted after her as she ran up the steps after Tonks. “You’ve got to come back in!”