Do 2 PG Diplomas equal a PG Degree?

It would all depend upon the nature of diplomas being acquired by you. There are a number of aspirants working in the IT domains with their basic degrees in Computer Science and further undergo for some diplomas to raise their standards such certification in Oracle and later taking diploma in Coding for the better grasping these domains but by doing so, their diplomas/ certifications earned cannot be equated with the degree of post graduation of computer science.
Though the case might be different of widening their knowledge with their total involvements of two different diplomas widening their knowledge in the different arenas to make themselves competent but in no way the same can be equivalent to any higher degree to be treated as the postgraduate degree holders.

No. Two PG diplomas are not equivalent to a master's degree. Already you have a master's degree that is MBA.
A person who did his/her basic degree in a certain area can go for additional diplomas or PG diplomas in related skills that will help him in developing additional skills in a particular domain.
These days there are many institutions offering various diploma and PG diploma courses in various skills and subjects. All of them might not have UGC recognition. So based on those certificates one can't apply for a job. But one can show them as additional qualifications obtained for skill improvement.
If you want to do a PG course, you should have a UG qualification in that particular subject and then you can apply for that.
But some jobs may be asking for a master's degree or PG diploma in a particular subject. If such mention is there in the advertisement you can apply for that.