Situation while "running it twice" during home cash game

[ivgotthenuts]

A situation happened during my home game last night that nobody was sure of the definite answer. An all in situation occurred between myself and another person and we decided to run it twice. I won on the first board, but on the second board we ended up splitting because of two identical straights.
Now here comes the Question. I won the first and tied the second. It seemed common sense that I should win 75% of the pot because I won the whole first board and then split the second board. The other person in the hand was arguing that it should be 50/50 split because we split the 2nd of the running it twice. After a somewhat heated argument for about 10 minutes, we decided to do a 60/40 split of the pot, where I got 60% and he got 40%. I would like to know if anyone knows what should have happened in this situation and if there are any rules for a situation like this. Thanks