If you are the laner faceing a 2 v 1
Golden rules, pro players do it all the time, it is called lane swapping, many do it willingly, and this is how they survive
1-pre level 6 they never push lane, they farm under tower
2-you make sure if you can't get the farm to at least get the exp
3-Keep track of play styles and patterns, this will be the difference between life or death, notice how they are playing and think of a plan on how to captalize on it
4-since it is a two v one, you will be leveling faster, the moment you are level six, ask for a gank and you and the jungler will be stronger for the enemy laners will be level five while you are both level six, or one level six and one level five oh and you both have offensive items.
IF YOU ARE THE JUNGLER
1-keap track of signs if the enemy laner is about to get dived, eventually the duo will go for a dive and you will want to be their to punsih
2-keep track of your laners items and levels, for eventually you both will be stronger
3-Use the fact you have no competition in the jungle to power farm, and do creative jungle path ganks