Matthew 28:19 (KJV)
Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost.
Name is singular. Does it mean that Father, Son, Holy Ghost all share one name?
I think name is singular and pertains to a single name of the Father, Son and Holy Ghost. In Acts 2:38 (KJV):
Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.
In the name of John, in the name of James and in the name of Joses can be rewritten as "in the names of John, James and Joses." If there is only one or same name of father, Son and Holy Ghost (Holy Spirit) it is possible that Father, Son and Holy Spirit is only one person?