As per page 12 of e brochure (pl see note below explanation to documents), the Study Certificate need not be counersigned by BEO/DDPI.  It is not necessary as per official clarification in this e brochure.  Take a print of this if required.

http://kea.kar.nic.in/cet2018/e_brochure_2.pdf

Hello Mahesh,

For the PUC certificate, (11th and 12th classes), a countersignature by the BEO/DDPI is not necessary or mandatory for KCET document verification so you don't have to worry about it.

Although, you have to countersign your primary and high school study certificate by the BEO.

All the Best!