Do you wanna see a couple kill each other? HA+
this is a yuri but its pretty funny and both girls are yanderes
http://www.mangago.me/read-manga/lovedeath/
Your request reminds me of.. someone ever asked for Tsundere x Tsundere which I just saw one but they're support characters. Their own story haven't been translated yet.
I think the main characters in this could both be considered Tsundere:
http://www.mangago.me/read-manga/kaguya_wants_to_be_confessed_to_the_geniuses_war_of_love_and_brains/
Does anyone know of any manga where both the characters in the main romance are secretly yandere?