The Grimorum Arcanorum has the emblem on the top only. However, these pictures certainly say otherwise...

For example, in the above pictures, the emblem switches sides. And just in case you're wondering... no, he didn't flip the book around. :P

It could also be on both sides. The third picture actually took place in between the first two screenshots. So yeah, it grew another emblem, and then lost the first one! And then it went back to normal for the rest of the episode! Well, it's a magic book. Does it really need a reason to do seemingly pointless stuff? :P