Notice the word another (allos = the same of a different kind) in this verse as compared to the word another (heteros = another of a different kind) in verse 6 (cf. 2 Corinthians 11:4).
In other words, they are not the same. The trouble that Paul is referring to here is the perverting of the true gospel which is troubling to those who hear it because it is contradicting. I believe that is exactly the problem in the church today in that there are still some that trouble you, by mingling the Kingdom and Grace gospels to the point that there is great confusion and misunderstanding.
On one hand, we tell them they have to repent, be baptized, and keep the Law, and then on the other hand, we tell them that it is not a salvation of works, but faith alone. Seriously? These are the same one that Paul is speaking about in Galatians 2:4; Galatians 5:10, and Galatians 5:12.
Verse 8: But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed. Notice, we, or an angel from heaven (1Timothy 4:1; 2 Corinthians 11:14; Ephesians 6:12). The Devil has always been busy corrupting the words of God (Gen_3:2-5).
A state senator from Georgia who calls himself a "Reverend" said the other day, "The meaning of Easter is more transcendent than the resurrection of Jesus Christ. Whether you are Christian or not, through a commitment to helping others we are able to save ourselves." That is flat out heresy!
Yet that is where we find ourselves in the church today, Dietrich Bonhoeffer, the minister who stood against Hitler's Germany once said of his students in 1939, "they are completely clueless with respect to what dogmatics is really about. They are not familiar with even the most basic questions. They become intoxicated with liberal and humanistic phrases, are amused at the fundamentalists, and yet basically are not even up to their level.”
The word accursed is the Greek word anathema which means to be cut off (Galatians 5:10-12; 1 Corinthians 16:22). Paul is pronouncing this on anyone who was telling them that they had to keep the Law to be saved.
Notice there be some that trouble you. This is referring to those who were perverting the gospel of Christ. To pervert means to turn or corrupt. These are mentioned in 2:4 and 5:12. They were the same ones that James referred to at the Counsel who were subverting souls (Acts 15:24). To subvert means to overthrow or destroy, undermine, render ineffective. Transitively it means to cause to serve a purpose other than the original or established one.