I am guessing this is the erroneous message glitch on the sims and your card won't be charged and you won't be receiving another sim, however if you do a CSA should be able to resolve it relatively quickly
@Pentico was the charge for the 2nd SIM card showed up on your credit card last week? PM has sent mass email by accident about sim card orders, many were in fact just wrong email but no sim card charge. I guess that was not your case, you actually got charged and got sent one.
Please open ticket with PM Support for a refund request