Yesterday I combined Javik's slam with Shepard's lash to produce a double biotic explosion.. twice, first by accident, second on purpose.
...and then I failed to reproduce it again. Will try again sometime today, but maybe I bugged out or something.
I just realized it might not have occured again because it happened when Marauders were in the battle, and they increase the armor of other mooks. In the other instances there were no Marauders so the first explosion probably killed the mook.
Okay, so this post spawned a big discussion about double detonations with Lash and Slam. I am somewhat peeved that I missed this conversation when it happened.
To re-iterate what you guys discussed, yes it appears that Slam has two distinct actions: the lift and the slam; the slam action will detonate biotic explosions. Lash apparently also has two distinct actions: the grab and the pull; the grab action detonates biotic explosions. So what you are seeing is: 1) Slam lifts, setting up biotic explosion; 2) Lash grabs, detonating the explosion; 3) Lash pulls, setting up a biotic explosion; and then finally 4) Slam slams, detonating the biotic explosion.
This was brought up on the forums over a year ago; doubtful I can find the original post. I made this video in response showing how it works. It was actually in response to someone who noticed Slam+Lash created double detonations and wanted to know if Lift Grenade with the Slam evolution would do the same thing (it doesn't).
I later did one of the N7 missions with Javik creating double detonations.