I guess the need for an Extra Header Row for the Deck View, must have been expressed before and it would really be necessary for mobile Views where the summary column is very little and the Two Headers are in so many cases too little to pass on the information needed.
But, if setting up a Third Header is not an option, would it be possible to allow the Secondary Header to display on two Rows?
So, if I make a Virtual Column as a LongText Type with a formula:
[Column 1 Info]&"
"&[Column 2 Info]
could it be allowed to enlarge the Deck and display the information of each column on a separate row in the Deck View?