As we know Moshe, upon coming down the mountain, was shocked at the sight of the jewish people sinning with the golden calf, thus throwing the Luchos - Tablets to the ground, breaking them to bits. These pieces were kept for all eternity within the Aron Kodesh.
Now we find in many places that the Torah refers to the Luchos as עדות - as testaments (Bamidbar 9:15 Rashi, Ibn Ezra Shemos 16:34, etc.)
However why were there still pieces left over? This would seem to be against to the Gemara in Gittin (33a) and many other places in Shas that states: עדות שבטלה מקצתה בטלה כולה - Eidus that is partly destroyed, is completely destroyed.
Thus Why were there still shards left? They should have been destroyed completely!