Pursuing two courses simultaneously in Distance Learning Mode

As far as your interest for the two courses- one degree and the other one being a diploma course is concerned through the distance mode is acceptable. UGC has circulated its guidelines and such perusal is not is not violative in nature.
You can even to the latest UGC notification in this regard for better clarity of their circulars.
However, you need to ensure that the two examinations which you are currently pursuing are not taking places simultaneously where there is the possibility of clashing of the dates of these examinations. If that is not the case, you may go ahead for such attempts.

There is no problem. You can do one degree and one diploma simultaneously in distance mode. Even you can do one in regular mode and the other one in distance mode.
In the year 2012, a committee headed by the then Vice-Chancellor of Hyderabad University recommended that a student enrolled in a degree programme under regular mode can pursue a maximum of one additional degree programme simultaneously under open or distance mode from the same or a different university. So you can do two courses without any problem. But your time and ability will have a say on that. You have to concentrate on both the courses and you should be able to complete the study within the stipulated time. As far as rules and regulations are concerned you can do that. Now you are the best judge to think about your abilities and decide. I wish you all the best.

There is no problem in attending and completing two distance education courses simultaneously but only thing is the timings are to be selected in a correct way so that there is no clash of assessments and exams in between them.
Actually UGC stipulations do not allow two regular courses simultaneously but allow one regular and one in distance mode simultaneously. Further, they have no objections for two distance mode courses to be undertaken by the candidates simultaneously.
Nowadays there are many online sites which are offering free as well as paid courses on various topics and learnings. Many professionals and career minded people are joining so many courses online simultaneously for increasing their skill levels and utilising it for growth and prosperity in their careers.
So, if one can manage his time and has a capacity for learning then one can definitely go for multiple number of correspondence or distance mode courses simultaneously.

I would like to post the response to an RTI I had filed with UGC to get a confirmation as to wheather we can pursue degree & diploma simultaneously in distance learning mode. Their response was as follows,

"regarding pursuing a degree and a diploma / certificate course simultaneously, UGC has
not framed any regulations."

In my telephonic conversation with the chief public information officer for ugc, I heard that they are formulating some rules on this & we can expect an update along with the implementation of NEP 2020 in a few months time. (probably by July 2022, by when NEP2020 is expected to be fully implemented)