Description:

    I travelled in the End and was hit by several Endermen. I was holding a totem of undying in my off-hand. The instant I was about to die, I drank a potion of healing II. To my surprise, neither the potion nor the totem worked. Finally, I had to respawn in the overworld.

    Then I changed a copy of this world into creative mode to see what happend. The results are:

        1. The potion was used but it didn't work.

        2. The totem is still lying on the ground where I died.

Important information:

    1. Totem held in my off-hand.

    2. The processes of dying and drinking potion occurred nearly at the same time.

    3. Totem wasn't consumed.

The following picture shows:

    I collected my lost items and find an empty bottle and the unused totem.