I noticed the use of both too, it's explained here: http://blogs.transparent.com/italian/tavolo-or-tavola/
I'm not a native speaker but i sing opera for five years. So I knew how to read italian long before i began to properly learn it.
Basically yeah, between two worlds, one ending and one begining with a vowel, the vowel are crunch in one ore more diphthongs. I will only differenciate between two e (you will say the two e wirh a little hyphenation and not abruptly cutting the sound) and when the world are not in the same sentence or clause.