See during the admission, the college puts stamp on the back side of the Marksheet. So doing lamination in marksheet can cause problem. But for caste certificate, usually such things are not done, still if you can get it unlaminated (it can be done) because during admission if they say that you won't be eligible then you will be in a problem. So as you have some time, you should remove the lamination from the certificate.

I hope this answer provides you some insight. Wish you a great eve!