Identical or Fratermal Twins?

Technically Shane and Jackson are fraternal twins. However, everything about them is the same- they are growing at exactly the same rate, they look the same, talk at the same pace etc. We are wondering if we should have their DNA checked to see if they are really identical twins- 15% of fraternal twins are actually identical. Dr. Yogman thinks that would be a silly exercise since they are their own individuals but as they get older we wonder more and more if they are really identical twins?