If you have a totem of undying in your offhand and in your mainhand and get fatal damage you Lose the totem in your offhand.

How to reproduce:

1. Put a totem of undying in your mainhand and your offhand
2. Make something happen that you die

What I observed: You lose the totem in your offhand.

What I expected: You lose the totem in your mainhand like on console edition and java edition. 
This is very annoying if you have a totem in your offhand and one in your hotbar. If you are about to die and switch to your totem in you hotbar it makes you have to put a new totem in you offhand. If this gets fixed players can switch to a totem in their mainhand to prevent losing their totem in offhand.