Resolved refresh rate of a 10.1" netbook

Hi,

In my Sony Vaio 10.1" netbook, running an Intel Graphic Media Accelerator 3150, I've noticed that the available refresh rates are: 59 Hz and 60 Hz. The screen resolution of this netbook is set to its maximum and recommended value. But if I change the refresh rate to 60 Hz, then it gets accepted but after re-opening that tab with the graphic settings it shows 59 Hz again. The drivers for that integrated card seem to be the latest. What's wrong? The monitor type is shown as Generic PnP Monitor and upon trying to search for drivers online it says it's using the best driver.

 

As an addendum: Would a netbook consume more battery power when connected to a multimedia projector? I'm going to use the Duplicate mode.
Also, is that proper behavior that the screen resolutions becomes automatically lower when using the Duplicate mode? Can this be changed manually to a higher value?

 

Thank you.