todomvc-data.js

// create the new TodoMVC instance:
// ................................................................
const todomvc2 = new TodoMVC();

document.body.append( todomvc2.rootElement );

// move the first todo from the first todomvc to the second one
// ................................................................
const firstTodoId = Object.keys( todomvc.data )[ 0 ],
	firstTodo = todomvc.data[ firstTodoId ];

delete todomvc.data[ firstTodoId ];
todomvc2.data[ firstTodoId ] = firstTodo;