IP difference among teammates? (NOT IP BOOST, NOT FWOTD, NOT LEVEL DIFFERENCE)

Honestly, the title says it all. I was playing a game of vs AI for the first win of the day bonus, and got 206 IP out of it. subtracting 150 from the first win bonus, I got 56 IP from the game itself.

So, it didn't make sense to me how this guy, same level 30 as me, claimed not to have the IP boost, and was not getting the first win of the day, got 134 IPs out of that same game. (I checked the guy's match history.)

he was constantly saying that kills give more IP, which I knew to be false, but I'm not so sure anymore (he had 27/1/4 cs173 and I had 20/3/3 cs116) I mean, even if we say that he had a IP boost, it should have given him double of what I got, which would be 111~113. and his IP is too low to be FWOTD too.

Rest of his records show that he gets ~200 IP per game, with non giving under 100 (lowest out of ten was 130ish) Can someone explain why this happens? Perhaps a bug or hack?