getting a friend for my new hamster

Question
i recently got a male siberian hamster exactly 5 days ago and housed him in a pretty large habitrail complete with tubes and ramps.. i initially just wanted one hamster but now looking at the size of the cage i'm know considering getting a second siberian, possibly a male as well, for a friend to share this huge cage. is it a good idea to get one or have i lost the opportunity in getting him a friend? since i've read its better to get them at the same time in the same cage.. is he already territorial with his cage after 5 days? or can he still adjust sharing his cage with a new friend or should i just leave him alone? also, if its possible to get him a friend - should it be male or female? last thing i want is bloodshed!!

Answer
It is VERY possible for you to still be able to squeeze in that second hamster at this point.  However I just want to make sure that you understand that both hamsters have to be of similar age and size.  You will also have to completely clean out the current home and wash every item in the cage before re-introducing the hamsters.  

The reason to do this is that in CASE your first hamster has already laid claim to some items, it will make them seem NEW again.  Introduce the hamsters into the cage on opposite corners and place a giant pile of food in the center of the cage (if you underfeed the hamsters then there will be issues).

Another thing you must always consider is the fact that nobody knows initially what personality your hamsters have.  For two hamsters to get along they must both be cool with the idea of sharing living space, however if you end up with a territorial hamster, then chances are they will fight.  Judging by how large you are making your setup sound, it seems to be ample space for two hamsters. Just make sure the hamster wheel is large enough for two hamsters or get two hamster wheels.