Question about duplicate images with unequal file sizes

Got a question here (and I'll try to be as concise as possible): How are images which are complete duplicates, where the only differentiating factor is filesize, supposed to be handled?

I just did a quick search for the duplicate tag, and found these:
post #281184
post #552031

The images are identical in every way, and the image's dimensions are the same also -- but, the images differ because they have different file sizes. To me, keeping both images seems kind of redundant (and duplicate/redundant images are frowned upon, I'm sure). So, what would be a reasonable course of action here, you think?

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As another example, let's say post #414762 (and yes, I'm aware it has a Child post. But the dimensions are different). As you can see, it is "PNG Overkill". Meaning, the filesize is huge, but the actual quality of the image does not match (I think you can still see artifacts in the image). I'm very well sure someone could upload the exact same image, with the exact same dimensions, but have a *much* smaller filesize, while still retaining the same quality as the image that it is duplicating.

If that were to happen, should the above image then be (essentially) superseded by the identical image -- which has the exact same dimensions and image quality -- with the smaller filesize instead?

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Sorry for all those question marks. And in case this thread is interpreted as a convoluted mess, here's what I'm basically asking in one sentence:

What is the general policy around duplicate images which only differ in filesize?

Thanks.

Actually between post #281184 and post #552031, post #281184 is slightly superior in quality. The lines are a bit less defined in post #552031 and the edges of where the water is on her body (especially on the legs) is less clear.

Hmmm, I guess I overlooked that (only spent about 15 seconds looking for a quick example), since I was just looking for a quick example. But upon examining it, what you say is true.

But regardless, would you still not consider having two (almost completely) identical images like that redundant? I know, in this case, they weren't completely the same, but I've seen quite a few others where finding a difference between the two was impossible.

Bapabooiee said:
Hmmm, I guess I overlooked that (only spent about 15 seconds looking for a quick example), since I was just looking for a quick example. But upon examining it, what you say is true.

But regardless, would you still not consider having two (almost completely) identical images like that redundant? I know, in this case, they weren't completely the same, but I've seen quite a few others where finding a difference between the two was impossible.

I was under the impression that they were allowed unless the duplicate you're posting is lower quality or a lower resolution.

NWF_Renim said:
Actually between post #281184 and post #552031, post #281184 is slightly superior in quality. The lines are a bit less defined in post #552031 and the edges of where the water is on her body (especially on the legs) is less clear.

Oh, that's just the jpeg artifacts added in when resaving at a lower quality. Other than that, they're exactly the same.

Scalar said:
I was under the impression that they were allowed unless the duplicate you're posting is lower quality or a lower resolution.

That's totally fair, I think. I'm pretty sure duplicate images that are higher quality/resolution are both allowed to stay (like post #467572 & post #532627), but I'm just curious about completely identical images where there is absolutely no noticeable visual difference what-so-ever except for the file size.

And as you said, duplicate images with a lower quality/resolution are not allowed, yes? That makes sense. But what if an image of the same quality/resolution is uploaded, has absolutely no noticable visual difference, but only has a (and I've said multiple times) smaller file size?

Would that then make the original inferior/redundant, or should they both stay, because the original was there first?

Here's a good example of different file size and nothing else:

post #396130
post #523364

The second is exactly the same as the first, except it was resaved as a png.