I'm writing this response on my phone so pardon any typos etc.
When we first started, and clients were hard to come by, both Amit and I worked with clients together. We both went on all showings etc. which was important for both of us to get experience etc.
Even then, it was difficult to make sure we didn't double call or tell the client the same info twice etc. We were both trying to do 50% of the job and it was just too difficult. We started taking "lead" on a client and one of us would be responsible for everything with the client and the other would be available as backup. The trust issue is huge here because we know that whether my clients generate more money or Amits, everything is split 50/50 and there is no ego about it.
More recently, it's become simpler to organize the clients as I am dealing with anything pre construction and Amit is dealing with anything resale. When a call comes in, we know exactly who is going to deal with it and we each have our expertise. And again, in terms of revenue, whether pre-construction generated 100% or vice versa, there is no ego from me or my brother that says "I made this money, it's mine" which is very very important when establishing partnerships. We work together and compliment each others skill sets, and that's what makes it a good partnership.
I have seen partnerships become a problem because the partners don't outline what is expected of each other ahead of time and they bicker because "I did more work than you on this deal" etc.
Clients can find it beneficial but it's not something we promote (we see agent partnerships highlighting 2 for the price of 1) - it's more of a background thing for us. Yesterday my brother couldn't make a client showing so I went in his place which was much better for the client than potentially missing the house they liked.