The "little-known fact" that the vomitorium was not actually where Roman went to make themselves sick so they could keep eating is by now common knowledge. Outside of this, however, would the Romans, or at least, certain Romans, truly eat to the point of vomiting and then just keep going? I recall in Seneca's Letters from a Stoic him recording his utter disgust at the sort of people who did that: was this something that actually happened, or might this just be a scurrilous rumour about some particularly immoral character that Seneca heard and wanted to believe?
Suetonius talks about this issue with Emperor Vitellius (16 April 69 – 22 December 69)
"He always ate three meals a day, sometimes four: breakfast, dinner, supper, and a drunken revel after all, which he was able te bear very well, by reason of regular vomiting."
From the tone Suetonius takes in this passage he makes it appear as though behavior is either uncommon or at least frowned upon by others, but I can't say for sure. I will look for a couple more sources and edit my post if i find anything else.
-Rome The Autobiography by Jon E. Lewis