question

Populating that list is probably handled by some internal logic that is not directly (at least not easily) accessible.

As a workaround you can run the code below when the model starts to copy all entries to the second list. For example by putting in a small process flow block that creates a token at time 0.

I tested the code with "Location" connections. It should work the same with the DropoffPoints, but you have to adjust the path in line 1 and the list name in line 2.

treenode listPartitions = Model.find("/Tools/GlobalLists/Location>variables/partitions");
List copy = List("Location_2");
for(int i = 1; i <= listPartitions.subnodes.length; i++)
{
    treenode partition = listPartitions.subnodes[i];
    treenode value = getsdtvalue(partition, "id");
    treenode entries = partition.subnodes[1];
    for(int j = 1; j <= entries.subnodes.length; j++)
    {
        copy.push(entries.subnodes[j].value, value);
    }
}