Is it ok to affix adhesive stamp on non-juduicial stam paper

Hi,

I used Rs.20 non-judicial stamp paper for lending money and affixed Rs.20 x 4 special adhesive stamp to appreciate the value to Rs.100.

My lawyer told me that I can't use this document in court as I affixed special adhesive stamp on non-judicial stamp paper which is not permitted. Is it so?

Is it legal if this individual agrees(in writing) to pay me Rs.1,60,000.00 after 1-yr for Rs.1,00,000.00 I paid him or is there any Usuary law making it illegal?