Antanaclasis is a rhetorical device in which a word is repeated and whose meaning changes in the second instance. Antanaclasis is a common type of pun.

Examples:

1. Put out the light, then put out the light. - Shakespeare in Othello.

This is said by Othello when he enters Desdemona's chamber while she sleeps, intending to murder her. The first instance of put the light out means he will quench the candle, and the second instance means he will end the life of Desdemona.

2. Your argument is sound, nothing but sound. - Benjamin Franklin.

The word sound in the first instance means solid or reasonable. The second instance of sound means empty.