Question Summary:
Can two people slaughter an animal together?

Question Detail:

If two persons together slaughter an animal (single knife held by two persons), but only one of them recites “Bismillah-Allah Hu Akbar “during slaughtering, is this fine from Islamic point of view??

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
If two persons slaughter one animal at once, it is required for both of them to recite a tasmiyah (bismillahi Allahu akbar). If any one of them intentionally leaves reciting the tasmiyah out, the animal will be haram.[1]
And Allah Ta’āla Knows Best
Muhammad Haris Siddiqui
Student Darul Iftaa
Melbourne, Australia  
Checked and Approved by,
Mufti Ebrahim Desai.