Hello,
Yes it is valid to do double PG in same course one through regular classes and one through distance learning.
Two Degrees at the Same time Valid?

In order to promotedistance education in India, the Distance Education Council (DEC) students can now be enrolled in the two degree prgrammes simultaneously.According to DEC, students can pursue two degrees through a combination of distance and regular modes, however, two-degreeprogrammepursued through regular modes is not valid.

Distance Education Council (DEC) taken the decision was communicated to UPRTOU vice-chancellor Prof AK Bakshi.

Please visit this link for details about it.
https://www.google.com/amp/s/educationbhaskar.com/education-news/two-degree-courses-simultaneously/7138/amp/
Hope it helps