Ribbi or Rabbi

From yesterday's daf Yomi (Eruvin 75b):

אמר רב יוסף תני רבי היו ג' אסורין אמר להו רב ביבי לא תציתו ליה אנא אמריתה ניהלה ומשמיה דרב אדא בר אהבה אמריתה ניהלה הואיל ואני קורא בהן רבים בחיצונה אמר רב יוסף מריה דאברהם רבים ברבי איחלף לי 

Rav Yosef taught a brayta in the name of Rabbi. But, due to an illness he had, he was somewhat forgetful, and students would need to remind him of things he had said and in what context. Here, Rav Bibi said to the other students not to heed Rav Yosed in this, because it was not Rabbi, but rather something he had himself reported to Rav Yosef in the name of Rav Ada bar Ahava, and gave the full context, that he calls such a situation rabbim in the outer chatzer. And Rav Yosef exclaimed that he had switched "Rabbi" with "Rabbim".

Ribbi or Rabbi?

Perhaps this can help resolve the dispute whether רבי in general, as a title, should be pronounced as Ribbi or Rabbi. See here at On the Main Line:

There are two dominant traditional pronunciations for "רבי" the rabbinic Hebrew word and title, as found in vocalized manuscripts of the mishnah and perpetuated in siddurim: ribbi (ribee) and rabbi (rahbee). Roughly speaking, Jews of eastern descent have ribbi and those of western, rabbi

After all, rabbee sounds a lot more like rabbim than ribee. But there might well be a difference between the title in general and Rabbi Yehuda Hanasi's appelation. Or maybe the sounds ribbi / rabbim were close enough.