I have never, ever heard of anything like this before. I didn't feel like that at all with my daughter. I actually was much calmer because I knew what to expect, how to breastfeed, how much work she would be, how much in love with her I would be.
You're never going to love your kids exactly the same WAY because they are different people, but you will love them exactly the same AMOUNT because they are all your babies.
I had to explain this same concept to my daughter when she was about 7 years old & said I loved her brother more than her. Her reasoning was because I yelled at her more than him. I explained to her that there was a reason for it & the reason was that when I asked him to do something, he got up & did it. The first time. He didn't put it off. He didn't ignore me. He didn't pretend that he hadn't heard me. He just went ahead & did whatever was asked of him. She, on the other hand, did all anything & everything to NOT have to do what I asked of her.
I told her I love her brother's brainy-ness, I love that he loves to read books, I love his humor & wit, I love his athleticism, I love his non-pickiness with food, I love that he's snuggly. On the other hand, I love her artsy-little-self, I love that no matter how much work it is, she'll do it so that she can have good grades, I love that she's a dancer, I love that she designs clothes, I love that she cracks me up every single day, I love that she helps me cook dinner. All totally different things, none more important than the other.
I asked her who she loved more, me or Daddy. She said she couldn't answer that because she loved us both. Well, of course, she loves that Daddy horseplays with them, but I tuck them in at night. He takes them to the park & I cook their dinners. He draws pictures with them & I help with homework & musical instruments. We're different people. She loves us both as much as the other, just in different ways.
It'll be the same with your kids.