Really funny jokes-Mix up

Sam was attending a conference in New York and staying at a very smart hotel. His wife, Sara, traveled down to New York to join Sam for the conference's closing dinner/dance.
When she arrived, Sam was still in a meeting so she introduced herself to the receptionist and asked for the number of Mr Wilson's room.
She was duly given the number and the key and she took the lift to the 3rd floor. Sara wanted to freshen up and be ready for Sam when he arrived back. She unpacked, popped her nightie under the bed covers, showered and got ready for the evening.
Time passed and Sara became concerned that he hadn't arrived back and she was worried as to whether they would make the dinner on time. By 8 pm she rang reception to ask if Sam was in the bar; she was told that he had gone to his room some 2 hours earlier.
“What room?” spluttered Sara to the receptionist.
“Room 205, on the second floor”, answered the girl politely.
“But I'm in room 409,” exploded Sara in consternation.
“Oh dear,” said the receptionist,"That must be another Mr Wilson's room!”
Sara grabbed her belonging and dashed down to room 205. She forgot, of course, to remove her nightie. What a surprise for Mr Wilson (and Mrs Wilson!) on returning to the room.