It is not Permissible to repeat Witr
Question :
Rakhs of Ramadhan at the beginning of the night and Rak'ahs of Ramadhan at the beginning of the night and in the last part of the night. What do you think of this action of his?
Answer:
It is not permissible to repeat Witr, because it has been reported in a Hadith:
There cannot be two Witr prayers in one night.
For the night prayer is prescribed as an uneven number (Witr) because Allah is Witr (i.e. One) and He loves Witr; so one should pray three, five, seven or nine Rak'ahs or the like.
If one prays in the Sacred Mosque and offers Witr with the Imam, he may pray one Rak'ah with the Imam in his Witr, then stand up after the Taslim of the Imam and pray another Rak'ah, then offer Witr in the last part of the night with the last Tahajjud - and it is preferred for the Witr to be his last prayer. But if he performs Witr with the first Imam after the Tarawih prayers, he should make the last Witr an even number so that he does not offer Witr twice in one night. And Allah knows best.
Source:
Ibn Jibreen
Fatawa Islamiyah, Vol. 2 Pages 316-317