Windows Phone and Windows 10 Mobile uses the serial number as part of the encryption for your sd card. You cannot copy it, or Windows will be unable to decode the data and it will be useless.
If you want to transfer it, there are 2 ways to do so that I am aware of.
#1: Using Storage Sense, move as many apps as will fit from the SD card to phone memory. Swap to the new card, and move them from phone memory to SD card and repeat this process until you have all your apps moved over.
#2: Uninstall all the apps, then reinstall after inserting the new card. You will likely lose user data for any apps that do not back up that data to the cloud.
Everything besides apps can be copied easily. Pictures, music, documents, and all that can be copied to a PC and then back to the new card.