He's not Obito, but there a possibility that Tobi has Obito's other sharingan.
I agree it is possible. Well anyways, we already got too many permutations on who is the real Tobi!
Kakashi's kamui and Tobi's kamui is very similar to Sasuke's MS.
Let me explain more in details why i think Tobi could be Obito or at least has his sharingan.
Sasuke's left eye can fire off the Amaterusu, while his right eye can extinguish Amaterusu.
Thus, left eye = offensive, right eye = defensive.
Kakashi's left eye belongs to the offensive type, whereby u see him using kamui to try kill Deidara or even teleport the nail sent flying towards him by Pain (the Kakashi VS Pain battle in Konoha)
Now,
Tobi's right eye belongs to the defensive type, whereby u see him using his kamui to ONLY teleport himself from places to places.
So, from here, u can see there is a connection between Kakashi's sharingan and Tobi's sharingan pointing it came from Obito.