:The feeling is mutual

I’m pleased to meet you.” “The feeling is mutual!” [=I’m also pleased to meet you]
من هم بهمچنین./ دل به دل راه داره

:it’s like they’ve formed a mutual admiration society

I can’t stand working with Tony and Linda. They praise each other from the moment they walk through the door—it’s like they’ve formed a mutual admiration society
اونا هی از همدیگه تعریف و تمجید می کنند / برای همدیگه تره خورد می کنند.

:back patting

They give each other mutual back patting

تبریک گفتن – تعریف و تمجید کردن