🔼The name Paarai in the Bible
The name Paarai occurs only once in the Bible. Paarai the Arbite is listed among the mighty-men of David (2 Samuel 23:35). The Chronicler, however, calls him Naarai the son of Ezbai (assuming that Naarai and Paarai are the same fellow).
It can no longer be estimated why one author calls this man Paarai while the other calls him Naarai (or why these mighty-men lists, or even the entire books of Samuel, Kings and Chronicles diverge in the first place). Both authors were working long after the time which they wrote about, and it seems unlikely that there where multiple, widely inconsistent sources (because the authors most likely worked off older sources, or else they would have had critical details wrong, such as the description of a 10th century temple).
Small discrepancies are often blamed on scribal error, but the Sleepy-Scribe theory is in itself debatable, and the difference between the names Naarai and Paarai isn't subtle. But it should be remembered that Biblical texts weren't always holy, and their genre was certainly not journalism (which wasn't invented yet). The texts of the Bible are compositions based on legends or earlier sources, which express the intentions of the author. It seems very likely that the Chronicler was trying to tell a different story than the authors of Samuel and Kings. And that's not at all a strange thing. In modern times we do the same thing with movie-remakes (like The Bourne Identity, which was a completely different film when Matt Damon played Bourne in 2002 than when Richard Chamberlain did it in 1988) or covers of songs (like I Will Always Love You, which was made into a wholly different entity when Whitney sang it than when the Doll did).
We can't answer the question of why one author speaks of Naarai the son of Ezbai while the other calls him Paarai the Arbite. It seems that after millennia of devotion and research, we still don't know enough about the Bible to fully comprehend it, its purposes and its inner workings.
🔼Etymology of the name Paarai
The name Paarai comes from the verb פער (pa'ar), meaning to open wide:
The letter י (yod) upon which the name Paarai ends, may either create an adjective (widely), a possessive form (my wideness), or may be a remnant of יה (Yah), which is short for יהוה, which is the name YHWH, or Yahweh.
For a meaning of the name Paarai, NOBSE Study Bible Name List reads Devotee Of Peor and Jones' Dictionary of Old Testament Proper Names proposes Opening Of The Lord. BDB Theological Dictionary does not offer an interpretation of the name Paarai, but does list it under the verb פער (pa'ar), meaning to open wide.