Hello student as IGNOU is an open university you need not to attend classes so yes if you're interested to do something else while pursuing PG then you can do is for sure. When it comes to appear in examination you have to make sure that both examination didn't clash with each other because in that case you need to appear in one of them and leave the other one.

I request you to please help me with the certificate course in which you're interested so that i can check and provide you the exact information about eligibility requirements and admission process.

Feel free to comment if you've any doubt

Good luck