LC in color?  

I have seen them
I don't know but I have seen something similar in an architectural book store in Chicago. It was several years ago, but what I remember was 2 or 3 LC-2 chairs in a turquoise leather (I don't think it was fabric from what I remember) and the metal structure was almost the exact same color! The chairs appeared to be very old. They were worn in and the metal had paint chips off of it. The same bookstore had 2 old barcelona chairs and a few of those extremely tall Rennie Mackintosh chairs.

i would guess
I came across an old catalogue (1987)of Cassina with old pics; lc3 in light brown leather with grey lacquered tubes, lc8 in beige canvas with green tubes. in the back is mentioned; "steel frame in polished chrome plated, glossy basalt, grey, light blue, green, bordeaux, ochre or matte black enamel, leather or fabric upholstery." Surely other colors where available when they were produced at 'thonet' (before 1965). + even the lc3 was designed for a luxury villa in 1928 i doubt that originally it was made in laether with chrome tubes.

Yea, they were produced in colors by Cassina
In the early 80's I bought one LC2 armchair with black painted frame (matte finish, like the base of the LC4) and the upholstery in khaki colored canvas.
The quality of the fabric was lousy, it wore out in a few years. And when taking a close look at the signatures a while ago I noticed that the frame was rather hastily painted too. The paint didn't cover the tube completely on the side where the signatures are.
On Cassinas website in the US they have a side kalled "Knock-offs"http://www.cassinausa.com/knockoffs.html
On my LC4 bought by an authorized dealer in 1975 there are no broad rubber bands but springs like the picture of "counterfeits". Even Cassina made the LC4 with springs supporting the mattress in those days.
The springs are OK, they haven't sagged but the rubber and the plastic covering the end of the rubber joining the springs have fallen off on some parts and made holes in the padding.
I recently saw pictures of an LC4 with a low number on eBay.de that had the same springs.
http://cgi.ebay.de/Le-Corbusier-Liege-LC-4-Cassina-No-7051-Ponyfell-blac...
http://cgi.ebay.de/fruehe-Cassina-original-No-2777-LC-4-Liege-Ponyfell_W...
Back to the question:
I also have an old Cassina catalogue from 1983.
There is a picture of an LC2 armchair with the tubes painted in some awful green color and the cushions covered with the same canvas as on my chair.
There is also one picture of an LC2 three-seater with black glossy tubes and a beautiful tanned leather.
One LC4 has the chrome frame completely covered with almost white fabric and no visible springs. The base looks like it's in two shades of gray instead of the usual black.
Obviously Cassina has made a lot of varities!