Too many duo games! MMR might be inaccurate?

so recently I've been duo'ing with a friend from work. like me when we first started playing he was in bronze. in the past month we have managed to climb out into silver. well recently he's been having a hard time with the LP system, he gets around 17LP per win and losses 20-21 per loss so I decided to look his profile up on op.gg and that is the title under his MMR check on the site. I'm just curious as to why. It's not like I carried him out completely by my own, he carried me just as much. just confused is all but then if I look up my profile it just gives me my MMr and says my mmr is "a bit higher than average" nothing about duo games. and I still get 20-21 LP for wins. so,, whats going on here?