Those are "tack hooks" The idea is that you slip the tack cringle directly onto the hook, and hoist the sail once in the foil or hanked on. Avoids shackles and pins quite nicely. The second hook is so that you can bend on another sail before dropping the first.
If you have a headfoil you can hoist a new headsail (smaller or larger, as the conditions dictate) before dropping the first and keep driving the boat - therefore you need the second hook in order to set that up. The longer flat part of the hook (which makes it somewhat less easy to slide the cringle over) also discourages having the sail fall off the hook between the time you set everything up and finally get to hoisting.
Many boats have similar setups at the gooseneck for reef tack points.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)