How does this happen?

Malevolan

It's happened a few times, but I get 2 points more damage when I do the tank raid than other people who solo it.
I do it in 2 teams (this time 3 because I wanted to see what Padme team could do in p1, wasn't impressed), CLS and Han for p1, A nightsisters deathstorm team with no zombie for p2-4.
Other people are soloing it in 1 team some JTR led team.

Kisakee

You already answered it yourself: you used multiple teams. That can glitch it out and add an extra point for every different team you use, in theory you can abuse it to get more points than others. Don't do that.

Malevolan

I don't do that intentionally, I do it because my main team does not solo phase 1 very well, and CLS doesn't solo phase 2 and beyond well.