Are you sure it isn't a storage card? It would be labeled SD and probably have a gigabyte label on it? Otherwise I would say it was an oops and somebody accidentally stuck a second Sim card in the box and it means absolutely nothing to you.
According to the Samsung Website
"New Galaxy S10 Models being shipped to Verizon customers are Dual SIM model (Hybrid SIM slot):
one Nano SIM and one Nano SIM and can be user converted by following the instructions included with the device to a single SIM and one MicroSD slot (up to 512GB) if the Dual SIM is not required for foreign travel"
I appreciate you sharing this information about what you are describing on your Galaxy S10 device, Dontan49. Let me see about what you are referring to and assist you. To clarify, are you referring that there was a extra small SIM card with your device? Did you purchase the device from us with a SD Memory card added to the order? The reason why I am asking is this device does have a SD memory card that can on the sim tray. Here's a link to the page on this device https://www.verizonwireless.com/support/samsung-galaxy-s10-e/ and you can pull up the User Guide to show the diagrams on the device. Does this help?