The extract is from B. Shaw's play "Caesar and Cleopatra".
CAESAR [cutting her short] I speak to the Queen. Be silent. [To Cleopatra] Is this how your servants know their places? Send her away; and do you [to the slave"] do as the Queen has bidden. [The slave lights the lamps. Meanwhile Cleopatra stands hesitating, afraid of Ftatateeta].
Why does do appear twice?