The E5470 only has the capability of a single M.2 SSD. You could replace the 128 GB SSD with a larger one and clone or image the smaller drive to the larger drive.
Hi just got a Lattitude E5470 .. It has a very small 128 SSD in it ..  But it looks like I can put 2 SDDs in it? as I could get a bigger one and run windows of the 128 SSD one? Thanks 
E5470 SSD drive upgrade