The infinitive absolute is a conjugation classified generally by a qametz under the first consonant, and a holem or holem - vav by the second. According to the Cambridge Introduction to Biblical Hebrew:
"A slight majority of infinite absolutes occur with a finite verb of the same root. These are called paronomastic. This construction usually heightens the verb's mood, i.e., its degree of reality, expressing certainty of emphasizing non - real mood. It can often be translated with adverbs such as surely, certainly, or clearly.
"You surely ought to drink - Jer 25:28 "
By this, then, it seems that the infinitive absolute is not superflous in the way it is commonly used, because it is serving a specific function, and the meaning of any verse would be slightly different without it.
However, many times in Rabbinic Literature, it is often seen as a redundancy, and expositions are made from that assumption:
"The double expression, die, you shall die (מות תמות) implies: death for Adam and deat for Eve, and by extension death for Adam and death for his offspring" - Bereshit Rabbah 16:6
"The verse concludes: eat, you may eat (אכל תאכל). R' Yaakov if Kfar Chanin said: With the double expression God was saying: When does an animal become fit for consumption? Once it is slaughtered. God was thereby hinting to Adam regarding the prohibition against eating a limb from a torn animal." - Bereshit Rabbah 16:6
"Rather, you shall surely bury him. This indicates that the post must be buried alongside the convict, and the post must be something that lacks only burial." - Sanhedrin 46b
So, does Rabbinic Literature misunderstand the infinitive absolute, by seeing it as a redundancy, when it is in fact significant to the meaning of the verse, or am I misunderstanding something about their method of exegesis? Is there any other way to convey the idea of "certainty" in Hebrew that wouldn't be seen as redundant? Are they holding two explanations, one being the simple meaning of the verse, and then holding that the word also has a deeper meaning, etc.?