@Nep The kanji in Japanese are:
「佐藤」 Satou (FMC's family name)
「砂糖」 Satou (sugar)
「武藤」 Mutou (MMC's family name)
「無糖」 Mutou (sugarless)
So they're homophones. That said, you guys could still be onto something given that they're described here as "sugary" (pink) and "bittersweet" (blue).