Really? cause the mortar pit greatly outranges the LeiG, especially with that new ability it which let it fire almost across the entire map (most 2v2 maps*).
I can assure you that 2 leig is a 100% counter pick against mortar pit. The only and sole reason for 2 leig losing to it is eithe (or both)
1. You did not seprate two - hence one mortar pit barrage kills borth leig - or did not "move" them to a different spot when mortar pit starts to fire at your leig.
2. you did not used barrage at all
They do require not-that-hard micro, but mortar pit stands no chance against 2 leig.
And heavy HE barrage is not really a concern if you just micro a bit. Especiallt because it has 1.5 ~ 2 x cooldown and you can't use normal barrage once it is on cooldown.