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I'm not too big on cats but I've been around enough animals to think that if they're both the same gender--they are, right?--it's sort of like one sees the other as a threat. They'll fight with eachother, but probably not to the extense of death. Just let them have at it until they figure out who's boss and things'll generally fall into place from there.
but that's just my thoughts on it.

-sorry bout some typos I'm in a sling and can only type with one hand Dx....

This sounds weird but take them to your vets and ask about anti-depressants. I had a clinical placement at a vets, and She was telling me how her two Ginni pigs were fighting and one almost killed the other. She put them on anti-depressants and they were best friends. She had a client that had the same problem but with dogs, they went on anti-depressants and they were best friends in like a week or so.

It's just that there is a new cat around. My roommate and I had our own cats and my cat freaked when we moved in, but whatever, they have to get used to eachother. My cat freaked on my dog when we introduced them but when they were in an open area instead of a small room, my cat would ignore the dog until they were in my room and my cat would freak. Thats because my cat thought of my room as his territory, and as long as the dog wasn't in there, they were okay.
If it's that bad, try and keep them apart, but in the same room.
If it's not that bad then just let them be and they will eventually love eachother. My roommates cat and mine now are gay lovers and they cry when one of them isnt around. They are in love and play and lick eachother and snuggle, but when they first move in together they didn't like each other at all.

And both the cats were around 10 months old when we moved them in, only one wasn't neutered. So it was the dominant cat and my cat was scared and wouldn't let anyone near him. He got better in around 2-3 weeks.