Please pay close attention to the bold words:
Ex 34:1 - The LORD said to Moses, "Chisel out two stone tablets like the first ones, and I will write on them the words that were on the first tablets, which you broke.
Ex 34:4 - So Moses chiseled out two stone tablets like the first ones and went up Mount Sinai early in the morning, as the LORD had commanded him; and he carried the two stone tablets in his hands.
Ex 34:10 - Then the LORD said: "I am making a covenant with you. Before all your people I will do wonders never before done in any nation in all the world. The people you live among will see how awesome is the work that I, the LORD, will do for you.
Ex 34:11-26: the covenant (2nd set of ten commandments) that god "[is] making... with [Moses]"
Ex 34:27 - Then the LORD said to Moses, "Write down these words, for in accordance with these words I have made a covenant with you and with Israel."
Ex 34:28 - Moses was there with the LORD forty days and forty nights without eating bread or drinking water. And he wrote on the tablets the words of thecovenant - the Ten Commandment
Notice the word 'and': it is not 'then' or 'after 40 days...', it means while, and verse 28 specifically states moses wrote the words of the covenant on the new tablets while he fasted for 40 days and nights, which god explicitly described in verse 11 through 26.
When Ex. 34:10 explicitly states God is making a covenenant with Moses, and 34:27 concludes the making of the covenant for Moses to write down, it can only be concluded that "the covenant" can only be that which is found between verse 10 and verse 27. If you do not think so, you are showing me a polymorphic interpretation, in which you choose to make it say something else which it does not.