It is not advisable. Rennet’s first role is to set the curd, and secondly, it remains in the cheese as a protease enzyme to develop flavour within the cheese (as proteins are broken down) and to modify the texture of the cheese as it ripens, e.g. it helps make your Camembert go runny and makes your harder cheeses less rubbery. If you add more than the required volume of rennet, you will get your firmer curd, which will solve your set problem, and you will feel good at this point of the cheesemaking. However, with an increased rennet volume, you will also get a greater rate of protein breakdown during the maturing of the cheese. Excess protein breakdown may cause bitter flavours to develop. This bitter flavour will then intensify as the cheese matures. Note some cheeses, such as Halloumi, can have high dosages of rennet but this rennet is destroyed with the 90°C cook step. What needs to happen if you are having problems with your set?  See the Blog article on this subject here