The narrative of Exodus in this place, all the way through to the end of the book, is very carefully crafted as there are two threads of narrative intertwined.
It must be carefully noted when Moses is upon the mount and when he is not. And when God speaks. And when The Lord speaks.
But, specifically, here - there is the matter of trumpets.
In Exodus the shophar trumpet is mentioned three times :
19:16 the voice of the trumpet exceeding loud
19:19 the trumpet sounded long, and waxed louder and louder
20:18 and the noise of the trumpet
This is in connection to the earthquake and the people being at a distance and the warning that man, specifically, (that born of Adam) and beast, specifically, (that which behaves in a beast-like manner) must not approach, under threat of death.
For humanity, in Adam (who chose a way of independent knowledge) and for any of beast-like character (who are mere feral animals) there is no approach to the Almighty.
But with earthquake and fire and smoke shall there be delivered to a chosen representation of mankind a covenant that will express on earth, in demonstration, the way which, in due course, God may be approached in the future.
Thus, during the execution of the first covenant, a glimpse of the everlasting covenant is revealed.
Hence the yobel, jubile trumpet is mentioned :
19:13 when the trumpet soundeth long, they shall come up to the mount
This is in the future. The jubilee trumpet had not - yet - been ordained by God to Moses. Five times is the yobel mentioned in Joshua, at Jericho, the blast of which seven trumpets brought the walls down.
Twenty one times will it be spoken of in Leviticus and Numbers in connection with the Jubilee and the return of all lands which have been leased out. At the sound of the Jubilee is there a release and one's inheritance, lent out in times of stress, returns to one's own possession.
And this trumpet is the one mentioned here. God promises that, at the sound of this trumpet :
ye shall come up to the mount.
The same careful narrative is observed regarding the tables.
Whether or not Moses wrote the second set of tables or whether God wrote them is difficult to determine and one has to compare at least two books of scripture to come to a conclusion.
But what God says in Exodus 34:1 is :
Hew thee two tables of stone like unto the first ...
and I will write upon tables ...
The KJV punctiliously inserts the word 'these' in italics, these tables, but it is not there in the Hebrew original.
There is one set of stone tables and there are ... tables (as yet undefined).
... this shall be the covenant that I will make with the house of Israel; After those days, saith the LORD, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people.
As the apostle Paul says in II Corinthians 3:5 :
Forasmuch as ye are manifestly declared to be the epistle of Christ ministered by us, written not with ink, but with the Spirit of the living God; not in tables of stone, but in fleshy tables of the heart.
There are two covenants here, not one.
And the people shall come up, at the sound of a trumpet of Jubilee - not terror - and only in sonship and priesthood (Aaron and Moses as sons of Levi) - not in the flesh of Adam, nor in beastly ignorance - and only after sacrifice and bloodshed.
Then shall they see God, and not perish.