1352 - Narrated Jaabir(may Allah be pleased with him): “A man was buried along with my father in the same grave. However, I did not feel content till I took him (i.e., my father) out and buried him in a separate grave.”.

Commentary : The martyrs who die for the sake of Allah [in the battlefield] are highly honoured in the sight of Allah, the Almighty. The Prophet ﷺ and the Muslims viewed the martyrs of the battle of Uhud, in particular, with special reverence. Abdullah ibn ‘Amr ibn Haraam, the father of Jaabir ibn ‘Abdillah(may Allah be pleased be with them) was one of those killed in the Battle of Uhud.
In this hadeeth, Jaabiribn Abdullah(may Allah be pleased with them) reports that his father was buried in the same grave as another man. It has been said that this man was ‘Amr ibn al-Jamooh ibn Zayd (may Allah be pleased with him).  However, Jaabir felt uneasy about his father sharing a grave, and so, he removed his father’s body from that grave and buried him in a separate one. All of this occurredwith the knowledge and permission of the Prophetﷺ.
It is reported inSaheehal-Bukhaaree that Jaabirremoved his father from the shared gravesix months after his burial, and he found his body in the same condition as on the day of his burial, except a slight change near his ear.This shows the merit and virtue of the father of Jaabir(may Allah be pleased with them).
From this hadeeth, we can conclude thatthat it is permissible to bury two men in the same grave, and also that it is allowed to remove the deceased from his grave after his burial, if there was a valid reason to do so..