In 3 out of 5 VARC mocks I score 30-32 but in the remaining 2 I get extremely poor score like 10 or 12, even when the difficulty is similar. I am not able to figure out my weak points as I use similar pattern to solve all the 5. Please help. This is bothering me a lot.

Mocks made by coaching institutes can only try to simulate CAT questions and their answers. They can deviate away from cat in trying to increase difficulty and I usually attempt a real cat or xat paper's VA section and that brings my confidence up again.

Mock scores don’t only reflect your knowledge and skill
But also your mental state. This might be the reason

Well, this is quite usual to happen with any aspirant. Just follow the process right, don't let low scores bother you as that can affect your preparations. Keep going, all the best Parul!