Tale of Two Tomatillo Seedlings - help?

[MSchep]

Anyone have any guidance on what could be going on with one of my two Toma Verde Tomatillo seedlings? These two have been side by side since i started them from seed 6 weeks ago (inside, under lights, on a warming pad), but the one on the right is thriving, while the one on the left is struggling (I'm calling him Left Shark, ).

I'm getting ready to plant them outside, but worried about Left Shark, since i've read that Toma Verde only does well in pairs.

Thanks in advance!