The rear brake line is one piece to the rear axle where it connects to a flexible brake line and then tees off to each rear brake. And use DOT 5 brake fluid in the future and you'll never have to worry about water in the brake lines! I've had DOT in my 70 Challenger over 30 years now!
Obash, follow your rear line after it leaves the distribution block. A two piece line will have another brass fitting attached to the inner DS frame rail, maybe 2 feet or so aft of the distribution block that you show in your picture.
Here's a pic of a two piece line for reference. The front of the car is to the right in the pic.
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Jeff K, I stand corrected, but there's really only one line going to the rear. Not two separate lines side by side which I thought he was asking. My bad.