TheOmegaAlpha said:
I was on the other day and noticed a sequence of images looked incomplete. I checked the source and found it was missing two images, so I grabbed them and uploaded them. I did my best to tag and following guidelines.
Surprised to find the posts deleted after getting on today, and curious I searched for the image to find it reuploaded by the user Cat-in-Flight.
I checked the reason for deletion, seeing the following: https://imgur.com/a/xukvZVy

The flag says inferior/duplicate, but the images are the same resolution from the same source, and were clearly posted first based on image number.

Incorrect. Your image is 1200x1200 the replaced images are 2500x2500

Conclusion: When you retrieve images from twitter, make sure you open the direct image in the browser, and add :orig to the end of the URL, this gives you the full sized image in comparison to the compressed image that the standard URL shows.

Your Post: https://pbs.twimg.com/media/Div3x0YUwAEV90L.jpg
Replaced Post: https://pbs.twimg.com/media/Div3x0YUwAEV90L.jpg:orig

Though do note, that it is still possible for the replaced image to be deleted as well, for if the image is of the same or greater resolution as Cat-in-flight's version but in a PNG format, than the twitter JPG would be deleted. As PNG files are better, and have a crisper image most times.