Never farmed the Matrix relics before, we can have 2 Matrix relics or its unique ?
It has little to do with farming, you just need to get the datacrons which have a matrix shard. It's not like it was a repeated process you have to perform over and over, you go there and take them, each is different. Personally I get all the datacrons on the planets I pass by. Some of them are useless (e.g. aim +2 on my primary character, a Jedi Shadow or the Sith Assassin this thread is about) but most have some use (presence and endurance are useful to any character, strength may be less important than willpower to a shadow or assassin, but it still increases lightsaber damage). A couple require you to be in a team, I know one on Quesh and one on Taris for which that is the case, requiring you to have three respectively two people to get them.
Paritcularly the ones on the starter planets are a simple matter of going there and taking them. Later ones require quite complicated jump-n-run stuff which can be quite frustrating at first, but once you get used to it, it comes naturally.
If you know which matrix shards you need, you might simply get those exact three shards, starting with those on the lowest level planets because those are mostly more simple to acquire. (Even though I know some on Coruscant which made me scream in frustration and others on Quesh that were simply laying about the place.)
But you can only have one.