That's effectively just a "Last Stand" effect (seems to be the most popular nickname for that effect on these forums) where an attack that might kill you doesn't, and leaves just 1 HP bar behind. If your alt had a large vitapod, you could better see what the true damage for that alt would've been.
This mostly means that if you also ever want to go into damage observations and calculations, it's best as well to ignore attacks that put you near death.
Boooo, alt user!