Yes, it does seem weird to have a caption and a description - you'd have to hope there's some sort of plan. Tx again.
No it does not seem weird to me to have both a description field and a caption field. For example the description might contain supplementary information which would not be appropriate in a caption. It might contain a further explanation, additional chronological information, background, provenance etc. In some cases it might contain technical details or, if appropriate, something about how some particular image was achieved.
There are all sorts of possible reasons to have both a caption and a description.