I think I differ from most people as I don’t usually take both. Little and Honey were a nightmare to transport together, Little was very dominant in his youth so would always get at Honey if they were too close so they only went together when it was necessary. Even then, Little used to prefer sitting on my lap on the way to the vets. If he didn’t sit on my lap the way there, he’d be shaking like a leaf once in the consulting room. As he’s got older he does better, I still allow him to go in and out of his crate as he pleases but now he generally prefers to stay in there and eat his hay, unfazed. He still tries to bust the carrier door open with his head though if it’s not open for him, lol. He goes for his incisors burring every 3 weeks, so it’s a good job he doesn’t mind the vets anymore. But Little and Honey never went to the vets together if just one of them needed it.
When Little and Peanut were together I think I took them both for a lot of appointments. Most of their vet trips were to the guinea pig dentist in Northampton and so since the journey was so long, and they usually both needed to see him, they went together. I believe Peanut only went there on his own once. He went to the regular vet on his own twice I believe and both were emergencies (one of which resulted in his death, unfortunately).
I think it can depend on the piggy to be honest. When Little and BB were together, I took them both when BB needed the vet as BB was petrified so needed a paw to hold.
Little is now with Digby and both boys are confident and comfortable and aren’t anxious at all so I probably wouldn’t take them both if one needed the vet. Not also that, but with how things are at the minute with the vets, they are very similar in description. Little is grey and blonde and Digby is black and blonde so I wouldn’t want there to be confusion on which pig is which.
With BB and baby pig (name still to be determined) they’re both as scared as each other so I have no idea what I’d do in that situation! Maybe I’d take BB if baby pig needed the vets but if it was BB then I might take only him and provide him comfort on my lap on the drive there.
If your piggies are comforted by being with each other, there’s no harm in taking both. In fact, it’ll probably be better for them. I think it’s down to character dynamics and what the piggies prefer