The Wedding of Sarah Jane Smith (1) - S3-E6
Corrected entry: Both Sarah Jane and The Doctor realise that the same second is repeating itself around them after seeing a TV clip of some racehorses. But both clips are identical, even though she is supposed to be a second behind him.
Correction: Both clips are slightly different. In the Doctor's one, the horse has just taken off in the clip, and in Sarah's, the horse lands.