Your sda2 should not be a SD card.

The information suggests that you have two disks; one sda (a hard disk) and a SD card called sdb.

I think I have been confused by you as I thought you just want a bootable SD card containing Ubuntu settings. To me that can only be the boot loader Grub and nothing else. If you want the SD card to contain a full working Ubuntu then it is something else.

You will need to check the Ubuntu forum on making a SD card version as it doesn't appear to be available from the general release the last time I tried it.

In your case you would be better to resize the partition to squeeze some hard disk space to create say sda9 and put the second Ubuntu there. The second can share the swap partition and just one partition will suffice. You can boot it as another choice in the Grub menu.

The problem with booting from an SD card is you must nominate the sd card as the first bootable disk before the PC Bios drops the booting to the hard disk. Therefore the SD card will take the sda device name and the internal hard disk is relegated to device sdb. You may have to change the internal settings when using the SD card and then revert back to the original setting if booting the internal hard disk first. You end up with more trouble than its worth.

Putting two Ubuntu into two partitions simplifies everything.