How do double D.Va ultimates work?

For example, if I am out of my mech, and then I can recall the mech. Should I get killed instead? If get killed instead I will have another mech and a more powerful ultimate.

Everytime I do my ultimate I can always get another mech quickly afterwards.

In fact there is a case where I ultimate, kill people, get another mech, get the mech destroyed, get another mech, and then ultimate again.

I have no idea how that works.

Do two ultimates get charged simultaneously? If so, then what's being displayed then?

D.Va is unique in that she has two ultimates. They charge separately.

Self-destruct behaves like other ultimates. It is charged by dealing damage and over time, while in her mech . It persists through death.

Call mech is reset to 0 whenever D.Va's mech is destroyed. This means that if D.Va is killed while on foot, she will not retain Call Mech charge. It is charged in the usual way- damage and time while on foot- relatively quickly. It is instantly fully charged when her mech self-destructs or if she is resurrected by Mercy.

D.va's interface and voice lines will only display and reflect the relevant ultimate. Annoyingly, this means there is no way to see her self-destruct progress while on foot, or waiting to respawn.