New GP not getting along with old one

Question
We had 2 guinea pigs: one was older almost 3 and the other about 9 months that we got from a pet store. The older one died. After a couple weeks we got a new one. This was a week ago. THey have fought every time we try to get them together. They are both males. Vet confirmed first one. The new one had a scab on his ear and I felt one on his back after we'd been home about a day; not from our old one though. We try every day to bring them together but they chatter their teeth at each other and sometimes attack. I am looking for any suggestions to get them to get along. Today I put them both in a neutral enclosed area. THe younger one squirted some milky liquid out his back side.  

Answer
Did you get them both from a pet store? Mites are common in pet store pigs as is URI. They may be making them irritable and causing them to fight.

What size cage do you have? Males need more space and at least 2 of everything in the cage. Have you seen www.cavycages.com?

Repeatedly introducing them and separating them only stresses them out more and forces them to do their dominance dance over. They need to work out who is going to be dominant.

Do you know how old the new one is? For a 9 month old boar, I would have recommended a baby boar, under 4 months old, but preferably 3-6 weeks old. An adult boar wouldn't hurt a baby. A baby isn't a threat to the adult.6 month old boars are teenagers and usually hard to match up.

It's too late now though. They may get along. They may not. You can build a C&C (www.guineapigcages.com) and put a divider up.

Read over: http://www.cavyspirit.com/sociallife.htm#Introductions

and

http://www.guinealynx.info/forums/viewtopic.php?t=2972

Also http://www.guinealynx.info/quarantine.html for future references and http://www.cavyspirit.com/petstores.htm

A guinea pig rescue would have helped you match them up.