Welcome to YT.
There are a lot of posts on this subject. Finding them is a challenge.
http://www.yorkietalk.com/forums/gen...2-yorkies.html
I have 2 males, & they get along very well, but the older one prefers to sleep & not play with the younger one.
A male will, in general, get along better with a female than another female. This is not absolute. The temperament of the individual dogs is important.
Similar size/weight is good, but not essential.
Neutering both should help.
How you introduce them is important.
Yorkies love Yorkies