It's not that you're such similar people, meeting life in the same ways; it's that you're able to appreciate the various experiences that the two of you have each gone through, and you find that you share an underlying energy that's basically similar in nature. Even though you might not be very similar on the outside, you still identify with each other, and you give each other lots of respect for the individual people that you are. You're both open to new experiences, so your differences don't seem threatening, but rather exciting.
Your needs are complementary, and there is a feeling of commonality between you, as if you want to help each other find the things you're looking for in a relationship. If one of you needs a lot of support and encouragement within a romantic relationship, the other is able to help provide that; if one of you needs independence or excitement or any of the myriad things that people need to feel comfortable in love, you're able to help each other find it and feel great about it. You're partly able to do this because of the great feeling of understanding and attraction between you; you talk openly about your experiences and your needs, and you're able to match things up for each other. This is a wonderful aspect to have in any romantic relationship, and it definitely helps in a long-term bond.