Yes! It is possible! An agent was filling in for an open house for a fellow agent who was out of town. She went into the WRONG house on the street. She entered the wrong home through the side door and made herself comfortable. She laid out her open house flyers and her cards and went around the house to make sure everything looked good. Thankfully, no one was home! Imagine her surprise and that of the occupant whom she may have surprised if there was someone home!!!
When did she realize her mistake? She had an appointment with a client who wanted to see the home. When this client did not show up, she called the client asking where he was. He told her he was at the house! The agent said I am here and asked what house number he was at and he told her the correct house number per the MLS listing. Realizing she was at the wrong house, she quickly left.
Moral of the story? Make sure you cross check the house number with the listing BEFORE you enter! Makes for a good story though!!