The answer is yes no no and it's not that easy.
First 50amp RV service is 50 amps at 240 volts divided so you get 12000 watts max
both 20 and 20 amp outlets are 120 volt so you get a max of 6000 watts
And I should have said Volt-Amps not watts but .. We will ignore that. (No they are not the same thing but you don't have the meters to tell the difference. I do)
So yes you can draw a maximum of 50 amps at 120 volts (6000 watts) with that set up. HOWEVER.. odds of hitting that are about the same a a snowball in an operating blast furnace.
For example I'd be surprised if that coffee maker draws 10 amps That's why
You would have to have very precise loading to hit 50 amp draw.
SOME campgrounds (Darn few) are properly wired. This means back at the distribution center EACH site has it's own breaker. If it's a 20/30 site then the will be a 30 amp breaker.. 50 amp sites have ganged 50's I've been in exactly ONE campground wired that way.