I don't know about it being normal or abnormal, but I taste during both. For example, I made a mix that has Cherry and Chocolate in it, and I taste the cherry on inhale and the chocolate on the exhale. I have no idea why...I just do! Several friends I've had try it say the same for them.
I have a suggestion for you though, since you've tried so many juices. Why not give DIY a try? I was vaping for 2 years before I even considered trying it. Now, since I've been doing it since just this past Feb. 2nd...I absolutely love it and kick myself for not trying it earlier!
It's not as difficult as many make it sound, and the initial investment can be less than $60 if you shop around. I bought everything I needed to make (10) 50mL bottles of eliquid for less than $56, and 10 bottles from my regular vendor I was buying from...would have cost me $140!
Plus, even after making those 10 bottles...I still had plenty of flavorings to use in more recipes! Also, some supplies (syringes, needle tips, etc.) included in that $56 can be used over and over again.
Just something to think about! DIY is definitely the way to go, especially for people who have a hard time finding juices they truly love. With DIY...you'll be able to find and have as many as you want!