w3c validation "Duplicate ID technicalProductFeaturesATF" error

Hi Artur,

it’s me again. I like your theme very much, and even more because it is w3c html 5 valid! There are not many valid themes around here.
But for a few days I got an error I cannot solve myself: Duplicate ID technicalProductFeaturesATF

I have no idea what this is and how I can solve it.

The complete error on w3c is:

Line 143, Column 38: Duplicate ID technicalProductFeaturesATF.

<div id="technicalProductFeaturesATF">

Warning Line 111, Column 38: The first occurrence of ID technicalProductFeaturesATF was here.

<div id="technicalProductFeaturesATF">

Is there a chance you can help me out here, too?

Thanks,
Chris