I think the suffix letters with Panasonic just indicate a color or origin/packaging.
E might be the lens when sold with the camera body, EE for a lens sold in display packaging. It's a lot like the K for black and A for blue or the suffix after a battery part number.
One lens might be the original taken off a camera and the other sold over the counter. It might even be just a later lens with the latest firmware installed from the factory. Same lens would be my best guess.
I only know of one 20mm f/1.7.