How can I copy multiple nodes and reset fields belonging to the copies in one operation?
In my opinion is easier if you write the code in a custom module.
You should create a custom form with form api with a button that call a function that select the nodes with db_select and after does the operations, copy :

// Load a node
$node = node_load(1);

// unset version and node id's
unset($node-&gt;nid);
unset($node-&gt;vid);
unset($node-&gt;path);


and unset values of the two fields for each node and save node

unset($node-&gt;field1);
unset($node-&gt;field2);
node_save($node);


After create a custom block and in block_view load the custom form.