your sample condition doesn't make any sense. you're checking to see if pos is < 10 and if it's > 20. Since you only have ands in the conditional, it can never be true, since each statement in the condition must evaluate to true.
Setting that aside, this might do what you want (assuming you update the conditional to match your needs.. i just made up some numbers). You'll also need to input a path (including file name and extension) for saving the new document.
var doc = app.activeDocument;
var newDoc = app.documents.add();
var newGroup = newDoc.groupItems.add();
var newDocFilePath = "/Path/To/File.ai";
for (var index = 0; index < 10; index++)
curItem = doc.pathItems[index];
pos = curItem.position;
if (pos > 10 && pos < 20 && pos > 50 && pos < 70)
duplicateItem = curItem.duplicate(newDoc);