Hi, I'm getting a duplicate response error (EResult: 29), when I call the following code.  
  manager.getInventoryContents(730, 2, true, (err, inventory) => {
        if (err) {
            console.log(err);
        }else{
          //other code here, never reached
        }
    });
This is run multiple times, but I need to be able to run it multiple times as the inventory is changing. How do I resolve this error ? Do I need a delay between requests ?