Can a glass plate act like a lens?

I am trying to implement rough dielectrics on my renderer. I compared the results of my renderer and Mitsuba renderer. However, a thin glass plate which is a cube scaled by (0.4, 0.4, 0.01) magnifies the object in front of it in Mitsuba while it does not magnify in my renderer. Do I miss something or does Mitsuba renderer do something wrong?

edit: IOR of glass is 1.1 and outside is air.

Result of my renderer:

Result of mitsuba:

• A thin glass plate should not magnify like this (if it did, you would see this every time you look through a window in real life!). Could you share how the glass plate is set up in your Mitsuba scene file? Perhaps there's something off about it. – Nathan Reed May 1 '18 at 21:24
• Here it is – Mustafa Işık May 1 '18 at 21:33
• Just a side note: IoR of 1.1 is a heavily unrealistic value for glass, which is typically in interval 1.5-1.6 causing much stronger refraction effect. – ivokabel May 2 '18 at 8:28

The box.obj file has no vertex normals, and by default Mitsuba will generate smooth normals for OBJ files that don't specify their own normals. This creates the magnification effect: the box with smooth normals forms a convex lens!
<boolean name="faceNormals" value="true"/>