I don't think they are looking for both. They are looking for what you achieved at your specific uni. They recognise unis grade differently.I usually take this to mean 2:1, 1st etc
At mine it was a % eg 72%
At a friend's their modules were graded A-D.
The classification usually is required when they ask for year 1, year 2 etc.
They don't look for the equivalents to be entered just have the options there to cover that unis way of grading. If it won't let you move without filling a box then you put N/A if you can or leave it blank if it does let you move on.
Edit- sorry I meant to reply to @IntoLaw