What causes my digi-clone's death to give me EXP?

Sometimes, when my Digi-Clone dies instead of just having the skill run out, I get a seemingly fixed amount of EXP from it. ~312 or so, as a Level ~30 Zane.

And seems to happen only / most often, while fighting Badass-type enemies?

But it doesn’t happen every time? What causes it?

I’ve got the Double Barrel… Might it be from the clone possibly killing itself due to me giving it Heavies?