If you mean a horizontal and a vertical view of the same abstract painting, yes. Because the site doesn't allow a customer to flip an image around like that. Be careful with titling though... you have to have a unique name for each.
if you want. as long as it can handle more than one orientation. though you should tell people you did that, just in case they get one vertical then think that the horizontal compliments it only to find out its the same thing.
be sure your uploading only sharp images that are large enough to print. this is too small and blurry. though you have no prices on it so i guess it doesn't matter. in fact i don't see any for sale, so you may want to look into that.
One of my uploads is a vertical crop of a larger, horizontal painting. I digitally added my name into the corner of the cropped version so it seemed to be more of a painting. I also have seen people put different versions of an image with the colors different or black and white. But it might be helpful to give an explanation to the variations.