We had two dogs until may last year when we lost our older girl
it was really nice having two dogs around, they were company for each other if they were left home alone, and they would look out for each other.
we got Jake when Missey was 10, she was a grumpy old girl, didn't appreciate a puppy jumping all over her, but she soon accepted him and they got on well, it is true what they say - introducing a younger dog can bring out a whole new lease of life in the older dog, and this happened with miss.
both had to learn things, the main one was that he learned to stay away from her when he wasn't wanted, but it was obvious that they cared for each other. towards the end when missey was ill, jake would keep going up to check on her & lay near her on my mums bed of an evening.
we worried about jake, how he would cope after losing missey, as he had always been with her right from being a pup, but he's adjusted really well to being an only dog as well. (probably hlped in part by his obsession with the budgie, did he not have the budgie as his friend, i think he's have got another pup by now!)
they were/are both border collies