There’s no harm in paying more than your credit card balance – it just means the credit card provider now owes you money, rather than the other way around.
If you’ve overpaid your credit card bill, it will show up as a negative balance on your statement. In this case, the balance on your statement will have CR next to it.
You can use up the credit as you spend on your credit card or, if it’s a large amount, you could ask your provider to transfer the money to your linked bank account.
While there’s nothing wrong with a negative balance on your credit card, it does mean that money is just sitting there. It could be put to better use in your current account.