In Charlie Puth's "If You Leave Me Now" (Feat. Boyz ll Men) at 2:40 Charlie performs a vocal run that is nearly identical to the run Justin Timberlake sings in the 'N Sync song "Gone" at 4:20. My question is if Charlie lifted the run or if it is more of an allusion or maybe just a complete coincidence. Side note: It is interesting how similar the time stamps are in which these runs occur in each song 2:40 and 4:20.
There are certain stylistic choices that can start out as personal idiosyncrasies, but become so widely imitated that they end up as genre markers. For modern pop/R&B, one of the most characteristic of these markers is "melisma," the singing of multiple pitches on a single syllable. Originating in the black gospel, church-influenced sound of soul singers like Aretha Franklin and Ray Charles, the modern improvisational melisma sound was exaggerated to what some might consider ridiculous lengths in the late 90s and early 2000s, notably by white R&B artists such as Timberlake and Christina Aguilara.
As with blues guitar riffs, the technique has become so stylized that it isn't uncommon to hear very similar runs in different songs by different artists. For a section of this brevity, I would consider this almost certainly unintentional. I have no doubt Puth has been influenced by Timberlake, but any conscious tribute is this particular song is unlikely. If he's consciously imitating anyone, it seems more likely it would be his backing singers, R&B vocal legends Boyz II Men (who predated Timberlake, and were doubtlessly a big influence on him).
As a side note, what sticks out much more to me, rather than the vocal run, is the lyrical similarity to Chicago's 1976 hit, also called "If You Leave Me Now." I wouldn't advise Timberlake to call his lawyer, but Chicago's lyricist might just possibly have a case.
'Cause girl, if you leave me now
If you give it up and just walk right out (oh)
You will take the biggest part of me
If you leave me now
You'll take away the biggest part of me