I found this and several other things in an article and they were helpful, so here goes.
This fragment explains that the second commandment doesn’t just teach the same thing as the first commandment all over again.
“The second commandment reads:
‘You shall not make for yourself any carved image, or any likeness of anything that is in heaven above, or that is in the earth beneath, or that is in the water under the earth; you shall not bow down to them nor serve them. For I, the LORD your God, am a jealous God, visiting the iniquity of the fathers on the children to the third and fourth generations of those who hate me, but showing mercy to thousands, to those who love Me and keep My commandments.’
In the first commandment God declares himself to be the only true God, who alone ought to be worshiped. In the second He tells us ‘the kind of worship with which he ought to be honored, that we may not dare to form any carnal conceptions of him.’
For as Calvin has said: ‘although Moses only speaks of idolatry [here], yet there is no doubt that by synecdoche, as in all the rest of the Law, he condemns all fictitious services which men in their ingenuity have invented.’” – Rev. G. I. Williamson
Bonus (this might be familiar, and it says the same thing about the second commandment):
