See if the miney is deducted two times for the payment under the same registration then Its usual that one extra payment wil be automatically redunded to your account with in 48 hrs or 3 official days. So wait for that. If you dont get the refund under the time period then I would suggest you to call the MHTCET contact number in order to get more formal informations and steps to be followed in order to get the money back.

For the MHTCET contact number visit the link provided below:

https://info.mahacet.org/mahacet/contact.html

For MHTCET preparations tips visit the link below:

https://engineering.careers360.com/articles/mht-cet-preparation-plan-and-tips/amp

I hope this answer helps. All fhe the very best for your future endeavors!