It will most likely lower your credit score temporarily (I've done it and it happened to me), but won't hurt you in the long run. So, I wouldnt open two at once if you're planning on muying a house or something in the immediate future. I have heard that some people open two credit cards from the same provider (two Amex, two Chase, etc) on the same day, and it only counts as one hard inquiry on your credit report. Bottom line, opening a new credit card will always ding your credit score slightly in the short term, so opening two may cause more of a ding. But, as I said, I have done what you are asking and my credit score is right at 800. I can't really advise you for sure either way unless I know more information about your life situation.