Electrical Questions? Ask an Electrician Online.
Hi, I'm Mike G and I'll be assisting you. What size wire is the feeder?
What is it fused for?
Why not wire the shed with #12 wire. It will be protected on a 20A circuit for both interior circuits without a panel.
It will be code compliant. The large feeder used to limit voltage drop is done all the time.
The only problem is being able to connect the #10 wire to both lugs. Can't put 2 wires in the lug and can't make a joint in a panel. A junction box is what is required.
One more thing. When you have a panel in a separate structure, a driven rod is required. A junction doesn't require one.