As per the UGC guidelines, a student can pursue two courses at a time provided one course needs to be in distance mode and one can be only in regular mode. So yeah! if you are think of doing BCA along with an online Diploma program, then obviously you can do it and both your Diploma and BCA will be valid.

For best online diploma courses you can consider visiting the link below:

https://www.careers360.com/courses-certifications/diploma-courses

I hope this helps. Wish you a great day!