Do magnetic money clips ruin credit cards?

My brother had his banking card erased by using a magnetic money clip. I think the issue is when the card slides over the magnets. If the card is just sitting next to the magnet it does not have the same problem. Basically, if you are really careful not to slide cards out, but to fully open the money clip first and then take the card out you will most likely be okay.

Another option is to use a non-magnetic money clip. I use one made by Superior Titanium www.superiortitanium.com. They have titanium money clips which are very springy and will return to shape to hold a single bill even after holding a larger number of bills and credit cards.