Some do two in one. (Please explain this in light of a Hadith if one exists).
In principle, there is no prohibition in Shari’ah to place the hand on the
head and chest and recite any particular Du’aa after Salaat. Therefore, that
practice is Mubaah.
The general principle of a Mubaah act is the person practicing on the act
should not regard the act as compulsory by insisting on its practice or
reproaching others who do not practise upon it. If he does so, that will be
an indication of the act to be necessary, hence, it will be distortion of
the Deen which is Haraam (strictly prohibited).
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai