A lactnut from S.Lake Tahoe asked me to share some of her info with you.
She is having problems posting directly to lactnet, so I am forwarding her message regarding feeding twins.

 From Patty Murphy  [SMTP:[log in to unmask]]
  Subject:      RE: breastfeeding twins

Chanita-I don't know the answers to your technical questions, but thought I would offer my own bf experience for your mothers of twins.  I am currently nursing my 16 mos. Old identical twin girls.  I had three other (bf of course) children when they were born, one not even 2 years old at the time.  So I knew that time would be precious and in short supply.  So I made the decision to bf them simultaneously.  Since I found adjusted bed pillows too cumbersome, I purchased the twin pillow  Nursemate (not My Brestfriend it is too small).  It helped tremendously and I still use it several times daily so it was well worth the money.  If one baby would wake up to nurse I would wake the other as well and nurse them together.  I never had to pump  nor did I have to use any formula.  It was a little difficult in the beginning to get them both latched on (I also had a c/s on the second twin).  But I was determined and knew if I got through the first two weeks everything would be fine. I noticed my milk seemed to come in later at about a week or else it was just that they emptied me so often that I didn't experience the fullness as quickly as had with the others. There was a time or two during the first 2 weeks when I questioned if I could do it as I was extremely tired and had actually had formula cross my mind (ever so fleetingly).  I am (obviously) glad I stuck through it all and would say breastfeeding twins was a much different experience physically, mentally and emotionally.
Physically:  with 2 nursing sometimes I would feel overstimulated in the nipples and didn't like the sensation.  I would just grit my teeth and get through it.  it wasn't painful just too much stimulation!!!
Mentally:  for about the first year I was zoned out (I compare it to being on a morphine drip or something).  I couldn't remember a thing and was in a hormonal fog.  Sometimes I couldn't even speak intelligently because I couldn't remember words or finish sentences.  Much less remember peoples names.  I am only now catching up on names and have to apologize to people I met during that first year. I came out of the fog at about 1 year as their solid intake grew.  I also developed an addiction to breastfeeding (maybe those hormones).  When I started feeling anxious or distressed the first thing to cross my mind was nursing.  I would grab the girls and go upstairs and nurse and within seconds  I felt this big calm wash over me, it was wonderful and very powerful.
Emotionally:  it is definitely the most rewarding nursing experience of my life.  To have nourished 2 babies for six months really gives one a big confidence boost.  I know that nothing else in life that I do will ever compare to breastfeeding all my children, but especially the twins.  I no longer sweat the small stuff, but that probably comes with the more children one has.
Also I would nurse them singley in public and now I often will just grab one and nurse, then when they other one notices what is going on she has  a tantrum until she gets in.
Sorry for being so long with this, but I am very interested in twins and sharing with other mothers.  Especially if they want to breastfeed.  No doubt you will get tons of comments from all the other m.o.t's on the list.  I am sorry to say that my sis in law had twins in December and didn't even offer the breast, not even a lick.  It breaks my heart!!!  
PS I enjoy reading your thoughtful posts on lactnet...Patty Murphy, s. lake Tahoe, Calif.
Almost forgot, I would breastfeed one twin on a particular side each day then switch the next day.  I knew it would be too much for me to remember from feeding to feeding which baby was on the left/right breast, but I could remember a whole days worth of feeding. I had one baby who ate more than the other and she was able to keep a full supply in both breasts.  Also I knew I had one breast that worked better than the other so it would not have been fair to delegate the "faulty breast" to one particular baby (I would have wondered if I was playing favorites).  
I think that last bit of info is an important thing to consider when making recommendations especially for people who have not breastfed twins.  It may not occur to anyone.  I would have posted to the list, but I am told there is something wrong with my messages (html coding???) so if you think the last paragraph is worthwhile to mention to others go ahead and post it yourself.   
One last thing on about day five I kept a 24 hr I &O log to be sure they were getting enough.  When younurse that much it is hard to tell.  Found I was only nursing about six times a day so increased it up to at least eight...