I say NO Paul DIDN'T teach another gospel but the ONE gospel delivered by Christ to the Apostles. Paul even check his gospel with the apostolic fellowship to make sure.
[Gal2:1 Then fourteen years after I WENT UP AGAIN TO JERUSALEM with Barnabas, and took Titus with me also. 2 And I went up **BY REVELATION, and COMMUNICATED UNTO THEM that GOSPEL which I PREACH among the Gentiles, but privately to them which were of reputation, LEST BY ANY MEANS I SHOULD run, or HAD RUN, IN VAIN.]
There is only ONE people of God not TWO
[Rms11:15 For if the casting away of them be the reconciling of the world, WHAT SHALL THE RECEIVING OF THEM BE, but life from the dead? 16 For if the firstfruit be holy, the lump is also holy: and **IF THE ROOT BE HOLY, SO ARE THE BRANCHES. 17 And if some of the branches be broken off, AND THOU BEING A WILD OLIVE TREE, WERT GRAFTED IN among them, AND WITH THEM ; 18 Boast not against the branches. But if thou boast, **THOU BEAREST NOT THE ROOT, but the root thee. 19 Thou wilt say then, The branches were broken off, that I might be grafted in. 20 Well; BECAUSE OF UNBELIEF THEY WERE BROKEN OFF, and thou standest by faith. Be not highminded, but fear: 21 For IF GOD SPARED NOT THE NATURAL BRANCES, take heed lest he also spare not thee. 22 Behold therefore the goodness and severity of God: on them which fell, severity; but toward thee, goodness, if thou continue in his goodness: otherwise thou also shalt be cut off.
23 And they also, IF THEY ABIDE NOT STILL IN UNBELIEF, SHALL BE GRAFTED IN: for GOD IS ABLE TO GRAFT THEM IN AGAIN. 24 For if thou wert cut out of the olive tree which is wild by nature, AND WERT GRAFTED contrary to nature INTO A GOOD OLIVE TREE.: HOW MUCH MORE SHALL THESE, which be THE NATURAL BRANCES, BE GRAFTED INTO THEIR OWN **OLIVE TREE? 25 For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that **blindness in part is happened to Israel, UNTIL the fulness of the Gentiles be come in. 26 And so all Israel shall be saved: as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob: 27 For this is my covenant unto them, when I shall take away their sins. 28 As concerning the gospel, they are enemies for your sakes: but as touching the election, they are beloved for the father's sakes. 29 For the gifts and calling of God are without repentance. 30 For as ye in times past have not believed God, yet have now obtained mercy through their unbelief: 31 Even so have these also now not believed, that through your mercy they also may obtain mercy. 32 For God hath concluded them all in unbelief, that he might have mercy upon all.]
There is only ONE olive tree whose roots are holy and we have been grafted into that ONE OLIVE TREE. When God converts all Israel, they will be grafted back into that SAME, ONE, OLIVE TREE, with the ONE people of God. In the ONE BODY AND BRIDE OF CHRIST, THE CHURCH.
[Eph3:4 Whereby, when ye read, ye may understand my knowledge in the mystery of Christ) 5 Which in other ages was not made known unto the sons of men, as it is now revealed unto his holy apostles and prophets by the Spirit; 6 THAT THE GENTILES SHOULD BE FELLOWHEIRS, and OF THE SAME BODY, and partakers of his promise in Christ by the gospel:]
[Eph2:11 Wherefore remember, that ye being in time past Gentiles in the flesh, who are called Uncircumcision by that which is called the Circumcision in the flesh made by hands; 12 That at that time ye were without Christ, being aliens FROM the commonwealth of ISRAEL, and strangers from the covenants of promise, having no hope, and without God in the world: 13 **But now in Christ Jesus **ye who sometimes were far off are made nigh by the blood of Christ**.
14 For HE IS OUR PEACE, WHO HATH MADE BOTH ONE, and hath broken down the middle wall of partition between us; 15 Having abolished in his flesh the enmity, even the law of commandments contained in ordinances; for TO MAKE IN HIMSELF of twain ONE NEW MAN, so making peace; 16 And that he might RECONCILE BOTH unto God IN ONE BODY by the cross, having slain the enmity thereby:
17 And came and preached peace to you which were afar off, and to them that were nigh. 18 For through him we BOTH have access by one Spirit unto the Father. 19 Now therefore ye are no more strangers and foreigners, but FELLOWCITIZENS with the saints, and OF THE HOUSEHOLD OF GOD; 20 And are built upon the foundation of the apostles and prophets, Jesus Christ himself being the chief corner stone; 21 In whom ALL THE BUILDING fitly framed together GROWETH UNTO AN HOLY TEMPLE IN THE LORD: 22 In whom ye also are BUILDED TOGETHER for AN HABITATION OF GOD through the Spirit.] I see NO evidence there are two people of God. When God converts all Israel they will be baptized into the ONE BODY OF CHRIST the Church.
[1Cor12:13 For by one Spirit are we **ALL BAPTIZED into ONE BODY, WHETHER we be JEWS or GENTILES , whether we be bond or free; and have been all made to drink into one Spirit.] By the Spirit are ALL BAPTIZED into one BODY, the Church.
Gal3:26 For YE ARE ALL CHILDREN OF GOD BY FAITH IN CHRIST JESUS. 27 For AS MANY OF YOU AS HAVE BEEN BAPTIZED INTO CHRIST have put on Christ. 28 THERE IS NEITHER JEW NOR GREEK, there is neither bond nor free, there is neither male nor female: for YE ARE ALL ONE IN CHRIST JESUS. 29 And if ye be Christ's, then are ye ABRAHAM'S SEED, and HEIRS according TO THE PROMISE