Hi Phil,
I missed the 60+ in the title originally, so this isn’t the issue I thought. It is still an issue, and maybe your history might help resolving it, but it is specific to 60+ Oysters where no fares are actually charged.
Paddington to Whitton is allowed 1 hour 50 minutes on weekdays so you just exceeded that time, hence it showing two journeys. Validators don’t know which way you’re going, so if you’ve timed out it will always start a new journey. Did your daughter make the same journey on a paid card? If so she’ll need to get it adjusted.