Various kinds of repetition contribute rhythm and emphasis to the poem. Lines 5-7, for example, contain polyptoton, anaphora, and epistrophe:
Of Fulbright Scholars. Just arriving—
Or arrived. Or some of them.
Were you among them? I studied it,
Polyptoton (the repetition of "arriving"/"arrived") highlights the speaker's uncertainty about whether the people in the photo were all just landing in London, or whether their arrivals had been staggered. Though this detail isn't particularly important—what does it matter to the speaker when these strangers arrived?—it helps reveal his overall lack of clarity. He starts with an assumption—that they're all just now arriving—then quickly questions that assumption, wondering if perhaps he got it wrong. A similar uncertainty surrounds other assumptions he made as a young man, including his superficial judgements about his future wife.
Anaphora (the repetition of "Or") also highlights the speaker's reassessment or revision of his memories. Both anaphora and epistrophe (the repetition of "them") add to the choppy rhythm of the passage, which, in turn, reflects the way Hughes's mind shifts directions and tries to home in on the truth.
More anaphora follows in lines 12-13:
The girls. Maybe I noticed you.
Maybe I weighed you up, feeling unlikely.
The repetition here again emphasizes the speaker's uncertainty: he isn't saying that he clearly remembers seeing Plath in this photo, only that he might have. If he did, he would have felt intimidated by her beauty and Americanness, which would have seemed glossy, "exaggerated," and foreign to a young man from the British countryside.
Later, line 18 contains repetition across a series of parallel clauses:
Grin for the cameras, the judges, the strangers, the frighteners.
Here, repetition builds rhythm and momentum, intensifying the speaker's statement. This intensity reflects Plath's anxiety about having to perform for everyone—a pressure she eventually buckled under. That she was "frighten[ed]" by the flashbulbs, "judges," and "strangers" is something Hughes understands in retrospect; at the time, he only saw her bright "Grin," not guessing what it concealed.