@RetroFreak89 One way to make sure that the extra space really doesn't contain any data is to shrink the second partition on the original sd card by 1 GB. But since this partition contains a Linux file system, you need a Linux partitioner like GParted for that (or a Windows partitioner that can shrink Linux partitions with the file system ext4 on them, if such a tool exists).
If you're not using Linux anyway, you could use the GParted Live image that boots from a CD or a USB medium into a graphical Linux system with GParted pre-installed.
After shrinking the second partition on your card, you would make a new image that has guaranteed no data in its last 1 GB and should be safe to write to your new card. After confirming that the new card works and has all the data on it, you could then grow its second partition with GParted to the maximum size of the new card.