3 green dock beetles wanting to mate

I was photographing, when i noticed these 3 green beetles. I immediately thought it must be 2 females and 1 male. I have no clue why there are 2 females though. Does one of them also want to mate? I'm not sure because i haven't seen behaviour like that in females. It was really cool behaviour though, so i took some recording, took my shots and one of them gave me this result!

 

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Species: Green dock beetles, groene zuringhaantjes 🇳🇱, syrebladbille 🇳🇴 (gastrophysa viridula)

Done