There's probably a few reasons hun. Most likely from being traumatized so badly by the first one and probably from being so afraid. Also with 'it not being rape in you head' you were probably trying to rationalize things to make them seem less traumatic... It's self preservation, I've done it before many times. Only its not self preserving.. In the end somewhere deep inside you knows it was rape, you know it was wrong and you have to find a way to know there wasn't anything you could have done that would make it not rape. If you didn't want it you didn't want it.
You should bring up how your feeling about this in counselling. Take Care.

some else posted something like this once....when we freeze it is our primitive nature....one of our bodies natural responses to trauma...just like animals. In the wild, when being attacked....they play dead on purpose...TO SAVE THEIR LIVES & MAKE THEIR PREDATORS LEAVE THEM.

I froze too once. I didn't want too. I kept telling myself, fight back, this isnt happening, but the experience was sooo surreal. It was like I was a spirit watching over myself...seeing the whole thing happen. All I could do is stream tears, lying there frozen. My voice got quieter and quieter throughout as I kept telling him to please stop, just stop and no. It was a whole lot of shock and disbelief...at the time, being raped.

I know I didn't want it though and I did tell him that and he did hear me. It's ok....we do what we have to....to survive. Whatever, subconsiously our brains tell our bodies to do, and put into actions. You are very brave and strong, don't doubt that for one second. You're a survivor & we're here for you ;)