Kennedy halves with different thickness

So I noticed that these two halves are very different in thicknesses.
The thicker one is a 2009 and the other is a 2003 with the same weight though.
Is it a mint thing or ????
I hope the picture can show what I'm talking about.

The thicker one is a 2009 and the other is a 2003 with the same weight though.
Is it a mint thing or ????
I hope the picture can show what I'm talking about.
