I was reading the article on here about Syrians not living together, and someone brought up her dwarf hamsters living together, and someone also brought up how to breed Syrian hamsters, so I thought I would post some information on this.
Dwarf hamsters are more social than Syrian hamsters, and can live together. It is preferable to buy them together at the petstore. If you have a lone dwarf hamster and you would like to introduce he/she to another dwarf hamster of its same species (I say this because there are many species of dwarf hamsters, Chinese Dwarf Hamsters, Winter White Dwarf Hamster, Robokian Dwarf Hamsters, and Campbells Dwarf Hamsters) you can do this via of the split cage method.
The Split cage method can be done several ways. You can split a ten gallon tank down the middle with strong screening fiberglass material, making sure it is very secure and your hamsters can't get to the other side. Then put a water bottle on each side and food and toys etc. Then put one hamster on each side, and swap them back and forth every few hours. By doing this they mark both sides of the cage as there terrortory and get use to each others scent.
Another way of doing this, you can put a smaller cage or smaller tank in a bigger tank and swap the hamsters back and forth (I have done this with gerbils it works very good).
Do this method for about a week or two, then pick a time when you can spend several hours with them and introduce them and watch them very carefully to make sure they will not fight. There is about a 50% chance this method will work, they will either get along or they won't.
Now two Syrians can not live together, so you ask how can you breed them? The female syrian goes into heat every 4 days, she will have a very musky scent to her when she is in heat. Put the female and male in neutral terrortory and watch them very carefully. If she is in heat she will go in a trance like state and they will start the breeding process, if she is not she will attack the male. Make sure to have heavy Mits or Gloves near by so you can seperate them if a fight breaks out.
I am thinking about breeding hamsters eventually, but the fact that they can fight scares me. I have breed gerbils in the past and this is so much easier, you introduce the male and female via the split cage method, and usually you can introduce them less than a week, and then they can live together, and usually then will have babies within 2 months.