There is no set rule that a brother and sister cannot share the same bedroom. But my advice to you would be to give them separate rooms if that is possible. As adolescents, they would like their privacy and you should respect the same. Their bodies go through changes and that may make it uncomfortable for them to be in the same bedroom. They might need their room to dress and might just be uncomfortable to have the sibling around.
So if space permits, it would be a good idea for your daughter and son to have different rooms.