Pushing unique data into vector

I have the following data:

FolioA Name1 100
FolioA Name2 110
FolioA Name3 100
FolioB Name1 100
FolioB Name3 106
FolioC Name1 108
FolioC Name2 102
FolioC Name3 110

I want to only insert unique names(i.e. Name1, Name2 and Name3, each once) into

std::vector<std::string> name;

as I iterate through the data.

So, I have the following code where I have stored the data in a map called test:

std::map<std::string, std::map<std::string, double> >test;
std::map<std::string, std::map<std::string, double > >::iterator it1 = test.begin(), end1 = test.end();
    while (it1 !=end1) {
        std::map<std::string, double>::iterator it2 = it1->second.begin(), end2=it1->second.end();
        **name.push_back(it2->first);**
        ++it2;
    }
    ++it1;
}

But, currently by pushing the data into name the way I am has 3 instances of Name1, 2 of Name2, and 3 of Name3, which is expected from my code. How do I fix it to only have unique names.