Yes, you can copy the bootable USB drive to another USB with EaseUS Todo Backup. Although you can't just copy and paste a bootable flash drive to another, you can easily achieve the goal by cloning.
Open EaseUS Todo Backup Choose the Clone method according to your own demands. Choose the bootable USB drive as the source disk. Choose the new USB drive as the destination disk.  You're allowed to edit disk partitions now or any time else after cloning.