'But even if we or an angel from heaven should preach a gospel other than the one preached to you, let him be eternally condemned(Gal1:8)
Paul and Peter preached the same gospel(Gal 2:6-9).
There is only one gospel!
If it was the same gospel, then why would God need another Apostle to preach it (Paul) alone (the twelve for the most part never left Jerusalem after Paul's conversion)? I mean, you'd think having 12 apostles to preach the same gospel would be enough, and then they don't even do what they're told (go out into the world). Why add a 13th? Wouldn't it be better to leave one in Jerusalem and send the other 11 out into the world, instead of not sending any of the twelve out and sending one into the world?
In other words, WHY PAUL?
Also, Galatians 2:7-9 specifically mentions two different gospels.
The gospel of the uncircumcised, given to Paul, and the gospel of the circumcised, given to Peter.
But on the contrary, when they saw that the gospel for the uncircumcised had been committed to me, as the gospel for the
circumcised was to Peter (for He who worked effectively in Peter for the apostleship to the circumcised also worked effectively in me toward the Gentiles), and when James, Cephas, and John, who seemed to be pillars, perceived the grace that had been given to me, they gave me and Barnabas the right hand of fellowship, that we should go to the Gentiles and they to the circumcised. - Galatians 2:7-9
http://www.biblegateway.com/passage/?search=Galatians2:7-9&version=NKJV
So either Paul lied about there being two different gospels, or you're trying to distort scripture to fit your beliefs.
I'M going to go with the latter, and believe Paul.