The Prophet (ﷺ) offered the Maghrib and `Isha' prayers together at Jam' (i.e. Al-Muzdalifa) with a separate Iqama for each of them and did not offer any optional prayer in between them or after each of them.
Sahih al-Bukhari Book 25, Hadith 153
← Previous Hadith Allah's Messenger (ﷺ) proceeded from `Arafat and dismounted at the mountainous pass and then urinated and performed a light ablution. I said to him, "(Shall we offer) the prayer?" He replied, "The prayer is ahead of you (i.e. at Al-Muzdalifa)." When he came to Al-Muzdalifa, he performed a perfect ablution. Then Iqama for the prayer was pronounced and he offered the Maghrib prayer and then every person made his camel kneel at his place; and then Iqama for the prayer was pronounced and he offered the (`Isha') prayer and he did not offer any prayer in between them (i.e. Maghrib and `Isha' prayers).

Sahih al-Bukhari Book 25, Hadith 152 Next Hadith → Allah's Messenger (ﷺ) offered the Maghrib and `Isha' prayers together at Al-Muzdalifa.

Sahih al-Bukhari Book 25, Hadith 154