Good Question! When we become filled with the Holy Spirit we will speak in a unknown tongue as a sign, or evidence of being baptize in the spirit.
Jesus told the disciples to be sure and not to leave Jerusalem, until they where baptized in the Spirit (see Acts 1:1-7) He was letting them know that they would need the power Of the Holy Spirit to do the work that was to come. In (Acts 2:1-13) the scriptures tell us that they were all together on one accord (with the same mind, or thinking the same way) when the rushing mighty wind came into and filled the house that they were in. Then they were filled with the spirit. (In Acts2:11) the people outside the room where they were heard them speaking in his own native language. It is important to know that when we speak this language we do not know what we are saying. It is when we pray, and we know what we are saying, that the thoughts of the world can distort or confuse what needs to be said. But when we pray in a unkown tongue it is to edify our spirit and to build us spiritually and a way for us to pray for others without knowing what to pray for. After saying all that. The answer is no we do not all speak in the same tongue. [/b]