The medical sense is dated; modern Chinese prefers 双性人 (shuāngxìngrén) or 间性人 (jiānxìngrén). The 'two-faced' sense is recent internet slang derived from 阴阳怪气 (yīnyáng guàiqì, sarcastic/passive-aggressive).
culture
On Chinese social media, calling someone 阴阳人 usually means they switch tone or position depending on their audience - not a comment on gender or biology.
