We got Tucker and Lilly at the same time... they were from two different litters born a week a part. I loved having two at the same time. Potty training was a little more of a challenge but I think the benefits out weighed all of that. They LOVE each other and I think they wouldn't know what to do without one another = )
Plus more yorkies to love, my family would fight over just one dog. We happily have three now and I can see considering a fourth down the road