I found a repeater than in a listing it says it accepts both, the 1750Hz tone burst, and a CTCSS code. Is this possible or is the listing wrong?
Sure, it's possible. It's most likely that it requires both - a 1750 Hz signal to wake up the repeater and a CTCSS tone as well. That's likely to happen when more than one nearby repeater uses the same frequency pair, and you don't want to accidentally key up both repeaters.
It's also possible that a repeater would react to either tone burst or CTCSS, but that would be unusual.