Check out this article. Apparently two college students were in a car accident - one survived but was in bad shape and in a coma, while the other died. The family of the dead girl thought their girl was the one in a coma, and the coma girl's parents thought their daughter died. They had a memorial service and everything. Now, some time later, the family taking care of the coma girl realized that she wasn't their daughter, and their daughter must've been the dead one.
What the heck?
Read the article here