Gray dwarf hamsters can be kept together without them tearing each other apart.  Actually, that's bullshit, I think, cause I have tried many times, and they always fight.  Save yourself a headache and keep all hamsters - both big and small, dark and light, brown and gray - away from each other. 

I did a couple of times let a large female hamster visit a gray male dwarf hamster's cage for a minute or two, and they sort of ignored each other.  She just went hunting for food.  She didn't attack him because she was a visitor to his cage.  He was curious and sniffed her, but went about his own business.  I have also put them together outside the cages with no conflict.  I wouldn't dare to let social gatherings last more than a few minutes though.

Hamsters live for three years, tops.  Amazingly enough, if a hamster dies other hamsters bury it.  Dwarf hamsters are small so you can easily flush 'em if they die.

This is Rachzak, named after my dear friend Rachel Zakoura.  My co-worker Jonette picked her out for me.  Jonette made an excellent choice, cause Rachzak was playful, friendly, and energetic.  Sometimes she was naughty in that she'd try to climb down from the couch when I wasn't looking.  She was a smart one, too, but she has long passed.

This was the original config of Rachzak's luxurious hamster Habitrail.  It's made of four separate Hagen Habitrail units, with additional tools and accessories.  Believe it or not there are hamsters out there that have more lavish homes than this.  Talk about overkill!  Actually, a habitrail can be a pain if you're not careful.  One time I tried to redecorate while I was drunk and I left a portal open, allowing Rachzak to escape.  When Rachzak gets away I typically find her in the dresser, in the drawer where I keep new bags of food.  Of course she busts open the bags by the time I find her.  As of this update, these cages now sit empty awaiting a new occupant.

Here's the Habitrail, currently waiting for a new occupant.

My friend Paul's fiancee thought getting hamsters would be fun, but like any new owner, she soon realized that it wasn't wise to get a male and female and put them together.  I took two babies off their hands and the female soon gave birth to two babies, as seen here.  Rachzak unfortunately had to give up two units of her home.  If you want dwarf hamsters to enjoy the tubes in a habitrail, you have to do a little extra work to accomodate their size.  I usually cut a piece of cardboard to the width of the tubes, cut slits in them to make them like ladders, and snugly fit them into the tubes, effectively reducing the tunnel room by about half.  Works great right until they chew it away and I have to do more engineering.   Hamsters are freakin' stupid like that.