Originally Posted by
YVR Cockroach
That used to be how a/c like the DC-10 and L-1011 were originally configured so you really had 4 pairs of seats a row, until the airlines started to add a 9th seat.
The L-1011 used to have a small partition between the "inner" pairs of seats. Inside the partition were coat hooks where you could hang up your jacket rather than stuff it in the overhead bins.
THIS PHOTO shows them on an AeroPeru Tri-Star.