Or HaChaim on Genesis 40:15/אור החיים על בראשית מ׳:ט״ו

1 כי גנוב גנבת, "for I have been kidnapped, etc." The reason the word גנבתי is repeated here is that Joseph endured a double kidnapping. His body was kidnapped, and the people who bought him were fooled because they thought they had bought a slave, whereas in fact they paid for a free man. As a result the people who had paid for Joseph did not really own him. Perhaps Joseph wanted to explode the myth that no slave could ever rule nor wear royal robes in Egypt by explaining that this did not apply to him seeing he had never been a slave (compare Bereshit Rabbah 89,7). Since Joseph realised that the chief butler's dream indicated that he, Joseph, would rise to greatness, he was insistent that the chief butler be aware that he had been born free, that his present status as a slave was due only to his having been kidnapped from his homeland.

2Joseph added גם פה, that even while in Egypt he was innocent of the charges that had landed him in jail. He explained that the so-called evidence of sperm on the gown of his accuser had been refuted by the clergy (compare Targum Yonathan ben Uzziel on 39,14). This is why Joseph later on treated the Egyptian clergy with extreme leniency during the years of famine (47,22). Had it not been for the clergy's objectivity at the time, Joseph did not need to make any concessions to them as Pharaoh had authorised him על פיך ישק כל עמי, that Joseph's authority extended over the entire nation (41,40).