R.C. Payne wrote:

If (at least one of) the tickets are zonal, the train doesn't have to
stop. In this case, both are, so no need to stop.

Both for zonal tickets. However, both are, so no issue.

I'm sure I read PTE zonal tickets are excluded, but TfL for some reason
doesn't count as that, so again OK so far as I know.

Neil