「、？」「、？」
"Excuse me, you're not Mr. Ogawa by any chance, are you?" "I am, what about it?"
Literal
"Possibly, you [topic-は] Ogawa-san is-not [question-か]?" "So is [but-が], something [question-か]?"
A two-speaker exchange illustrating common casual/polite formulas. もしや ('possibly,' 'perhaps,' 'by any chance') is a slightly formal/literary softener used when guessing someone's identity or asking a cautious question — more polite than もしかして, more tentative than maybe. The question ~ではありませんか ('aren't you X?') is a soft, polite way to confirm a guess. The response そうですが、何か？ is interesting: ~ですが trails off with a contrastive が, and 何か？ ('something? / what?') is a slightly curt 'what is it?' — the combination conveys 'yes, and?' or 'I am, but why do you ask?' with a faint note of suspicion or protective reserve.