I have to Yorkies one is 2,6 yrs old and the other is 7 months old (boy & girl).
If you get two it will be rally good that they grow up together...however it is double the work, expenses, etc.....it a bigger responsibility.
However the pros are that they enjoy each others company, they´ll play together will cuddle and also entertain themselves (at times)....you will also get doubble the love, kisses and licks
i bought a doubble leash so i could walk both of them at the same time with one leash!! (it is very handy)
Theyll still need a lot of your time to play and will look for lots of love and attention!.