Yes our 3 m/f pairs used to be like this. Now 5 of them live together!
I think it's more protecting their territory than actually disliking the other buns they see! Ours lived in 3 different housing types - each 3 foot apart on the patio and they only got tetchy when the another pair were on free run time and actually got up at their mesh! Then the male always used to tell his girl off for fratanising with another boy through the mesh :lol::lol:
Which ever pair it was they were all the same, all are neutered, but they behaved this way! Yet amazingly none of them minded when Toshi housebun used to pop out to see them! They all knew him from a baby, and he knew them - some better than others. His mom, brother Earl and sister Smokey obviously knew him. Then his auntie Rosie and Uncle Joe who he used to visit with Smog, as he was bonded with their previous chum Smog who suffered headtilt / EC - she couldn't live with them but they groomed her when she and Toshi visited for 5 mins or so several times a week
Finally Broops - who when he got kicked out of the outdoor group, was befriended by Toshi who leapt into his cage and sat eating hay with him - they had met previously through mesh etc - but the jumping into Broops cage happened accidentally - yet Broops didn't bat an eyelid and Toshi just sat eating Broops hay! This really amazed me, unfortunately Toshi had been unwell for months and passed not long after this, but he took a shine to Broops and vice versa without any bonding or signs of aggression - especially from 2 males - this really opened my eyes to how much they crave interaction with their own kind!
Infact the only bun Toshi really disliked was his brother-housebunny Crackers. As we hoped to bond them so they could free range together round the house - I'm sure this dislike was more for our inconvenience :lol: Bless em!
The outdoor group of 5 get tetchy with Crackers and Piper being out on the patio and when Broops and Petunia go out too... I really do think it's territory..