Actually I have gone through trial and error method in the link you said. And below are the findings
If the specialisation are same in two degrees/ diplomas's they will treat it 4 year bachelor's
If there is specialisation changes then they treat it a different education
Now for my b-Com they have mentioned in specialisation in "Business administration"
I have mailed to them to change spealisation to accounts rather
Let's see if they change the report only than I will get PGD as different education