The simple answer to this is no. There have been a few questions of this nature where people have been paid twice in error/been credited inadvertently by their bank etc and they always seem to think that they are entitled to keep the money as it has been paid to them in error. This line of thought is completely wrong and you have a duty to return any money paid into any account of yours by mistake. Look at things this way, if you did an online payment into a wrong bank account by mistake, would you be happy for the person receiving the money to think they are entitled to keep it as you are the one who paid it to them by mistake?
There is a very high chance that the credit card company will realise their error once they check their accounts. There is also a chance although a small one that you could be charged with theft if you spend the money credited to you in error. A case of this nature got into the papers as the woman who kept the money given to her in error by her bank was sent to prison.
Also in this case I would not recommend that you put the money into a savings account while you wait for them to discover it, as the likely case is that they will simply put this as an outstanding debit on your account from the time that you withdrew it and then charge you their very high interest rates for the total debit which is bound to be higher than any interest rate that will be offered in a savings account.
My recommenation is for you to contact the credit card company and let them know of the error. You can take the moral high ground and give them a good telling off for making the mistake in the first place!
Hope this has helped.
Cheers Sue