double free or corruption (out) on returned value

I'm geting double free or corruption (out) error on line "output = crosingOperator(parentA, parentB, begin, len);". This happens only for big sizes of parentA and parentB (They're always in same size) and not every time.

crosing():

    std::vector<unsigned> geneticAlgorithm::crosing(std::vector<unsigned> parentA, std::vector<unsigned> parentB, int mode)
{
    std::srand(std::time(nullptr));
    std::vector<unsigned> output;    
    unsigned begin = 0;
    unsigned len = 0;
    int rand1 = std::rand();
    int rand2 = std::rand();
    int parasize = parentA.size();    
    if (mode == CROSSING_MODE_HALF)
    {
        begin = (rand1 % ((parentA.size() - 1) / 2));
        len = (parentA.size() - 1) / 2;
    }    
    if (mode == CROSSING_MODE_RANDOM)
    {

        begin = (rand1 % (parentA.size() - 1));
        len = (rand2 % ((parentA.size() - 1) - begin));
    }
    output.reserve(parentA.size()+10);
    output = crosingOperator(parentA, parentB, begin, len);    
    return output;
}

crosingOperator():

std::vector<unsigned> GeneticAlgorithm::crosingOperator(std::vector<unsigned> parentA, std::vector<unsigned> parentB, int begin, int len)
{
    std::vector<unsigned> tmpA;
    std::vector<unsigned> output;
    tmpA.reserve(parentA.size());
    tmpA.assign(parentA.begin() + begin, parentA.begin() + begin + len);    
    for (int i = 0; i < parentB.size(); i++)
    {
        for (unsigned value : tmpA)
        {
            if (parentB[i] == value)
            {
                parentB.erase(parentB.begin() + i);
                i--;
            }                    
        }    
    }
    output.reserve(parentA.size()*2);    
    std::vector<unsigned> part1;
    //std::vector<unsigned> part2;
    std::vector<unsigned> part3;    
    if(parentB.begin()!=parentB.end())
    {
        part1.assign(parentB.begin(),parentB.begin()+begin);        
        part3.assign(parentB.begin()+begin,parentB.end());
    }    
    output.insert(output.end(),part1.begin(),part1.end());
    output.insert(output.end(),tmpA.begin(),tmpA.end());
    output.insert(output.end(),part3.begin(),part3.end());    
    return output;
}