Both carbs have 2 needle and seats.
The single feed has a transfer tube and has side hung floats
The dual feed has 2 fuel lines and center hung floats. It flows more fuel than the single feed.
A single feed will work fine on a mild 440 for the street.

72 Satellite Sebring Plus 440, 72 Dart 5.9 4-spd, 68 Valiant, 73 W200, 78 D100 sb, 78 D200, 98 DAKOTA, .
Moparmarks Parts & Restorations
Desert Mopar Metal
Grand Jct. CO
970-261-7039
http://moparmark.com/
motormangj@gmail.com