Béchamel and pomodoro
In Italy we usually mix béchamel and tomato sauce for "Pasta al forno" (or "pasta pasticciata") and lasagna, in order to not have a full distinction in the final dish between the two sauces and their tastes.

However this is not mandatory, but my grandma, my mum and me are used to do it (and I see some other people doing the same).

P.s.
I live in Italy and I'm 100% italian :-)