Similar images, different artists

post #1422542 from clearite vs post #1420736 from efyuru, both rating:E

I'm not knowledgable about either artist, and don't speak moonrunes, so what's up here?

Artists' comments:

光のアイカツ！おじさんの皮をかぶったつもりでいる闇のアイカツ！おじさん事くれりてさんの線画。塗ってみました。ほら、本性出しちゃいな！

いちあお＋りんごさん

描け麻雀こわい…りんごママ本原稿募集中です…（∩ω∩）

I'm guessing maybe a collaboration or something?

The lineart is on Clearite's twitter.

Sometimes artists put out lineart that anyone is free to color in as a derivative.