1.If you will play around with name Obito, swap the letters, leave the "o" out and there you go! "Tobi" 2. Tobi has ONE sharingan and Rinnengan. Why? Before his death, Obito gave Kakashi one of his sharingan. 3. As you see, Obito was fatally crampled by stones, what takes him recovering. So it's possible that he recovered in 20 years! 4. No one must know that Obito is Tobi, because that will lead to a massive stir.
Tobi has one sharingan now, because he lost his other in the battle with Konan (look it up if you want). Name playing is not proof of anything. Furthermore, edo-tensei Madara suggest he is familiar with Tobi on a personal level, thus making Tobi far too old to be Obito. Chances of him being Obito are about 0%. just sayin.