Dear Swapneswar,
As already stated there is no such mandatory requirement to maintain RG23-A and C seperately except to maintain a consolidated Cenvat Credit Account which is also not a statutory one. According to me majority of the assessees are only maintaining a consolidated Cenvat Account except, few assessees who are still following the old procedure in some places.
I suggest, in your case if, you are still following the old practice of maintaining RG 23-A and C, you can continue the same and there is no issue .
As far as taking credit is concerned, I suggest you to take the same in RG23-A since, the Rule itself is clear that credit on capital goods upto the Value of ₹ 10000/- per pice, credit can be taken considering that they are inputs. However, if , you have any concern , you may also take in RG23C.
Best Regards
Surya