Depends on the keycard. Some will erase other cards close to it while others will not. I just stayed at hotel and they specifically warned me that their card will erase others near it. Also, you need to consider the wallet that you are using. (Dont make the mistake of buying an eel skin wallet, they look nice but I ended up with a load of bad cards - this was several years ago).
My cards haven't shown any negative effects from keeping my access card in my wallet.
Not much of an issue these days since the magnetic stripe on the back uses high coercivity materials that are pretty hard to erase even with common magnets. Didn't used to be the case. There are still some antitheft systems that use a high mag flux to inactive sensors at checkout but these are less common now. Eel skin wallets demagging credit cards is an urban myth,
@cashnocredit wrote:Not much of an issue these days since the magnetic stripe on the back uses high coercivity materials that are pretty hard to erase even with common magnets. Didn't used to be the case. There are still some antitheft systems that use a high mag flux to inactive sensors at checkout but these are less common now. Eel skin wallets demagging credit cards is an urban myth,
I stick by my wallet of deads cards as there maybe more truth to this than myth. (of course, it could had been something else but I still blame the slimy eels)
