it is quite obvious they have been attacking each other and the guppies in my opinion.
i had 2 males (brought in a group of females) live together for near a year, i didn't know they were males until i seperated 1 of them, they never used to seperate always together but they were also brothers.
I know that they can not be kept together and I'm not going to. But don't you think its such a shame. How pretty would a tank with 4 or 5 different coloured male betta be?