So I just got the iPhone XR and I was replacing its SIM card with the old one from my iPhone SE - long story short I don't know which is which anymore. How do I tell which SIM card is the new one from the XR and which one is the old one from the SE?
Only one will be active. When you activate a new one the old one is deactivated because you can only have 1 SIM active at the time.
There are instances if duplicate SIM cards, but usually only for paired devices and for Digits lines.
Also, if you still have the card the SIM came in, the numbers on the backside of the card and SIM will match.
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