Should the congregant who wishes to pray and perform Witr with another Imam remain with his first Imam and perform Witr with him, or is it permissible for him not to perform Witr and to leave this Imam and await the other Imam? And is this action wrong?

Whoever prays Tarawih with the Imam until he leaves will have the reward of spending the night in prayer, and this is a great virtue. So, whoever desires this virtue and performs Tahajjud after Tarawih has two options: either pray Witr with the Imam and then pray as much as he wishes without repeating Witr, or add a second rak'ah to the Imam's Witr after the Imam's salam, then pray as much as he wishes and perform Witr at the end of his night. The Hanbalis have permitted this, even though it is better for someone who performs Tahajjud to make their Witr at the end of the night, but there is flexibility in this matter.