¡Hola tocayo! ("tocayo" is a person that have the same name as you, we both are David haha)
I'm not sure if I've understood you. An example could be:
¿Abres tu la puerta? - ¿Tu abres la puerta? <- parece una sugerencia, pero por el significado.
¿Escribiste tu la carta? - ¿Tu escribiste la carta?
Actually I think that most time, it doesn't matter unless you want to stress the subject.
If I haven't undestood your question, at least you have 2 extra examples haha. Kind regards!