A 12-year-old girl was praised for her efforts in English in a report from school - an impressive achievement considering she was not a pupil there.
She also had a letter from an education welfare officer concerned over her absence, even though she was in lessons at another school.
Sophie Bond was praised for her performance in English as well as being told she excelled at technology at Patcham High School, Brighton. Sophie goes to Oakmeeds Community College in Burgess Hill.
Patcham High has apologised for what it said was a clerical error.
Sophie's mother Diane Bond, 42, was initially amused when the report, dated December 6, was posted through her door.
She said: "At first I thought it was funny and so did Sophie.
Then I began to take it seriously and now I am angry that a school can be so careless.
"The staff don't even know if my daughter is one of their pupils."
Sophie went to an induction day at the school before the beginning of this academic year.(July) Her mother decided she would go to Oakmeeds instead and they moved from the Seven Dials area of Brighton to Hurstpierpoint.
That did not stop Patcham High compiling a report for her for the entire term.
It said she was well-behaved but mentioned one slight area for concern, which was that she might be finding it difficult settling in.
It suggested teachers arrange a home visit with Ms Bond to discuss the problem.
Ms Bond complained to the school when the letter arrived but said she never received a reply.
Janet Stuart, chairwoman of the governors at Patcham High, denied the school had sent out a report.
She said: "The girl was marked down absent for a couple of weeks as a clerical error and the education welfare officer followed that up but found the family had moved on. It wasn't a report, it was a letter that had been written at the end of this short period of when she was being marked in the register. I haven't seen the letter but it was an acknowledgement that she was at the school. It was purely a clerical error that has now been rectified."
A school spokesman said: "The pupil in question had been registered here but due to an administrative error her name was not removed from our records when she chose to attend a different school. Unfortunately we mixed her up with a different pupil with the same first name. We are updating our systems as a matter of urgency and have apologised to Ms Bond."