Sorry but this is insane. The instruction for such pads should say, like the notice shown at Highbury & Islington Northern City Line / Victoria Line interchange (not the exact wording):
National Rail ticket holders only
If you are travelling with Oyster / Contactless pay as you go and using another ticket for the remainder of the journey, touch here to start or end your pay as you go journey in order for the correct fare to be charged.
Furthermore, all the promotional materials for PAYG users specify that only touch the yellow reader at the start and the end, and all pink readers en-route, so it should be clear enough that yellow readers should not be touched during the journey.
The existence of continuation exits, which puts the card in a state of both inside and outside the system, solves nothing that can’t be solved by prominent signage, but creates so many problems that even RPIs are confused.