Forum:King of the swamp ruling

<!i have been troubled recently from dueling a friend who uses E heroes. As he fuses for a fusion summon, he fuses 2 king of the swamp, now is that possible? He states that as long as the fusion card does not say "This card can only be fusion summoned with the above material monsters" then it is alright. i am guessing that may be true, but i still have my doubts. he also states that both king of the swamps effects are like looping each other. Since king of the swamp could be used as any fusion material, the other one(s) must be correct, but the other king of the swamps effect kicks in saying it could be used as any fusion material meaning would it be correct also? So it leaves me confused as to if it is true or not.....HELP ME CONCLUDE THIS! THANKS>