I'd centre it over the sofa area -- i.e. take it closer to the small window. (Bit difficult to say exactly what 'the sofa area' is, but I mean over those three cushions on the right.) It doesn't matter at all if the lamp is slightly in front of the art, but you wouldn't want it to overlap too much.

That's what I thought also. Sorry didn't get a photo before I took it down, with the new light. Did you have any thoughts on the spacing between the two?

About half the distance -- or even a bit less - than you have them in the first pic. Sorry, I should have thought to address that.

Try an inch or two more. If you have a (continuous) diptych, it needs to look like a diptych -- as Leslie says, "one painting almost". This is a bit too almost. But it must be close enough for the eye to join the images up.

I like this example of a continuous-image diptych hung well.

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