Most houses have 120/240 volt service. The 50 amp RV is identical to these.
Look at your breaker box.. Now depending on the box your main breakers will be either at the top. on the left or in the middle.
Generally if they are in the middle then breakers on one side are L-1 and the other L-2 (Which is which is kind of arbaratary)
if they are on the end then it's 1.2.1.2.1.2
If they are on top well
1 2
2 1
1 2
is common also
1 2
1 2
Depeding on the box if "Mains" flip up and down and the branch sideways
Then the top configuration is likely.
Push-matics (Never seen an rv with 'em) use the bottom.