This name Yahshua came from scripture scholars and hearsay. There is no historical or scriptural evidence for the name of Yahshua, but there is for the name of Yahweh.
Why would Yahweh, the Father, who gave his name to his only begotten son, also give it to someone else? The son inherited the name of the Father, which is above every name. That name is Yahweh.
There is no way he will accept a watered down version of a name that's supposed to be his. There is no way that Yahshua (Joshua) of the Old Covenant had the same name as the Messiah of the New. What really blows my mind is in Acts 13:6 it speaks of a sorcerer, a false prophet, a Jew, whose name was Bar-Yahshua. You can believe he had the same name as the Messiah's, but I never will.
I would like to add something else on the name of Yahshua. They say it means Yahweh our salvation, which I have no argument with, for it is the meaning of this name. Now I will show you why it's not the Messiah's name. The name Yahshua is too confining in that it could never mean anything else but what it means. I'll show you what I'm talking about. In the Old Covenant Yahweh was called by the following:
Genesis 22:14 - Yahweh-Yirah = Yahweh will provide
From the above verses you can see that they show his name Yahweh and the offices which are: provider, banner and peace. As you can see his name never changes only the office. If you take what he was called in Judges, Yahweh-shalom and made is Yahshalom this name could never mean anything more than Yahweh is peace. Here again, Yahshalom being a name in itself, is not the name of Yahweh. When Yahweh returns to redeem his people, he will be to them Yahweh the redeemer or Yahweh-gaal. In Jeremiah 34:16 it says that Jerusalem will be called Yahweh-tsidkenu or Yahweh our righteousness.
Surely you can see by now that Yahshua is a name in itself and is not the name of the Messiah. The Messiah's name is Yahweh and he is Yahweh-shua or Yahweh our salvation. His name never changes only the office. You don't take his name Yahweh and add shua to it like this Yahwehshua, by doing this you have made a compound name that is completely different form the original and here again made it confining.