I'm not able to say, but each twin would be fertilized by their own sperm cell.
That would be correct.  Each egg has its own sperm cell
Do you happen to know any twins? I do not, do you and would they be fraternal twins? Fraternal twins are those who each got fertilized by a sperm cell. What is the difference between fraternal and identical? Identical twins develop from one zygote, while fraternal develop from two different eggs So I guess then boy/girl twins are always fraternal.
In fraternal twins, each twin is fertilized by its own sperm cell.