Recently a new twin mama from my multiples club was feeling guilty about how one of her babies was demanding so much more attention than the other. I think this is a very common problem with multiples, and one that really tugs at the heartstrings. Here are my thoughts on the issue...
I know the feeling! I had a similar situation. I felt like everyone who visited in the early days always got to hang out with Delia, because she was so much calmer and easygoing. And also that she spent a lot more time in bouncers, swings, on the floor, etc. Elsie was my fussier & needier one then, and she was always nursing, in arms or in a carrier on me.
The best piece of advice I latched on to is the concept that "fair is not equal" (and "equal is not fair"!). Meaning, with twins (or just siblings), each baby/kid will have their own needs, that just will not be the same, and it wouldn't be right to treat them the same. The amount of time you spend with each kid will vary depending on the hour, the day, the month, the year. As they get older, you will need to spend more time helping one with sleep, or another with eating (or math, reading, soccer, etc!). This seems totally obvious when considering different age siblings, but it certainly applies to same age sibs as well!
When they are so young, it really is harder to not feel guilty about, but do trust that if the baby seems happy and content, she is! And that this time will pass! My more needy baby (Elsie) turned into the more easygoing young toddler (for the most part) and is now the one that can easily transfer to others/accept new situations, and my easygoing baby (Delia) is a lot more hesitant and tentative about new things now as a toddler! I am sure they will flip flop over and over as they get older.
Some tips, though:
-If you can put the needier baby in a carrier or sling, that helped me a lot. Around 3 months I was able to put her on my back in my Beco carrier and then I had more hands/space to interact with my other baby or my toddler.
-When you are holding one, still face the other baby towards you in the bouncer or whatever and talk to her often, make eye contact, etc. I found just talking to her a lot helped me feel like she was not being ignored.
-Set aside special times to hang out one on one with the less needy twin. I would take her on outings or errands by herself sometimes (because she was so much easier to travel with!) and that was fun and good for us both.
Someone else in the group (I cannot claim this one but wanted to add it here as well!) made the very good point that you also should sometimes just LET the Needy Baby fuss or cry while you take a turn with the calmer baby, and do not ALWAYS tend to Needy Baby first. Excellent advice! I definitely did that a lot as well (or took that a step further and tended to the older sister, letting both babies fuss or cry, ha ha!). Now, though, all three of my girls are amazingly patient, which I think is a pretty great (and necessary) character trait in our family.
Any other tips from my mama of multiple readers? Or just mamas of more than one?

