יג אמר רבא ומאי קושיא דלמא שאני מעילה דילפא חטא חטא מתרומה מה התם שלוחו של אדם כמותו אף כאן שלוחו של אדם כמותו
13 Rava said, But what is the difficulty? Perhaps misappropriation is different, for "sin"/"sin" is derived from Terumah tithing. Just like there, the messenger is is like the person himself [who sent him, in that as long as the person sending is the owner and allowed to separate terumah tithes, so can his messenger], so too here [for misappropriation], a messenger is like the person himself [who sent him]. [Thus, our Mishna isn't needed to teach this non-innovative teaching.]