This isn’t something I’d have noticed unless I was staring directly at these few pixels, but it looks like the Tantive’s engines are in front of the Star Destroyer for the first few frames of their overlap.
I’m not sure I see it, but the Tantive layer is most definitely below the Star Destroyer’s, so if that’s the case then it’s a problem with the original composite of the film and there’s not much I can do about it without doing some serious Frankenstein work, which I think is overkill for something that is probably in the '81 version anyways.