Not on the inside and outside, which is unusual and unnecessary, but on the inside only, some of the ten commands being written on the right hand, and others on the left, not for any mystery, but only for conveniency of writing.
Related Commentaries of Exodus 32:15
Exodus 32:15
15 And Moses turned, and went down from the mount, and the two tables of the testimony were in his hand: the tables were written on both their sides; on the one side and on the other were they written.