Why are "bg2.jpg" and "bgalt.jpg" included in the /static folder?

a grep over the codebase for "bg2.jpg" and "bgalt.jpg" doesn't show any usages of these images in the code...is there any reason to keep these in?

these appear to be statically served on all pleroma instances, e.g.:

https://pleroma.soykaf.com/static/bgalt.jpg

https://social.im/static/bg2.jpg

which doesn't seem nice given the somewhat questionable content of these images

deleting these images doesn't seem to impact anything on a pleroma instance, but i'm not sure if these are intended to be used during fail-over or anything...