I have this code i am doing for university. The first code works as expected, the second one provides different results.

I can not see what they are doing differently??

first:

public Mat3 getNormalMatrix() {
    return new Mat3(this.getInverseMatrix()).transpose();
}

second:

public Mat3 getNormalMatrix() {
    Mat4 mat = this.getInverseMatrix();
    Mat3 bla = new Mat3(mat);
    bla.transpose();
    return bla;
}