Blood on the Debate Floor: It’s not usual.
That said, it has nonetheless happened and occasionally still does, especially in the early days when any hint of the sort of sentiments that led up to the Drowning of the People reoccurring would tend to lead rapidly to the defenestration of the misbegotten wight who proposed such a thing. (The Defenestrative Gallery is now on the public tour.)
And when particularly sensitive topics arise, some Senators – especially from more hot-blooded or kinesthetic species – have been known to start the odd brawl.
The Guardians of the Senate always finish it, though. What, you thought those weapons were ceremonial?
Although when it comes to protecting the Senate from itself, at least they usually stick to the electrolasers.