erection vs erect_penis

i'll just ask if the erect_penis tag is a redundant one? there appears to be a wiki entry but it's just a link to erection. i would suppose erection is the real main tag. if this is correct, i'm willing to edit the entries since there are only few. but 3 posts are not visible in my part.

then if it's also possible, i would request a tag alias erect_penis -> erection so not to isolate the posts in the future. thanks.

I don't know how Danbooru plans to use it.

But outside reality:
An "erect_penis" is probably always a penis.
An erection is not always a penis though.

Aliased to erection for now, since images that are ambiguous about whether a real penis is involved can be covered in that, but not necessarily in erect_penis.