It's not about double moves and blocking them. Double spaces are about accommodating larger groups of players and making sure scoring options remain competitive. It's all about balance.
Without double spaces, players in a 4/5p game would be very limited in the spaces they could land on and, therefore, their strategies for scoring would be limited too. For example, one or two players could quickly take an early lead in Panoramas or Temples, closing that strategy for other players. Having double spaces in some (but not all) of those locations opens things up, keeping other players in the game, but it still doesn't mean everyone can stop everywhere.
Bear in mind that not every space on the road is a double space and double spaces still can't accommodate all players (two at most, as the name implies).
As for who comes out first, if a player decides to occupy a double space on their turn, they're still the last player on the road, they still haven't leapfrogged at least one other player. Therefore, they get to go again. I don't see why this is problematic.
In any case, the manual is clear on this in both the language used and the illustrated examples: last in, first out, same as the Inn. I don't see where the confusion comes from.
Without double spaces, players in a 4/5p game would be very limited in the spaces they could land on and, therefore, their strategies for scoring would be limited too. For example, one or two players could quickly take an early lead in Panoramas or Temples, closing that strategy for other players. Having double spaces in some (but not all) of those locations opens things up, keeping other players in the game, but it still doesn't mean everyone can stop everywhere.
Bear in mind that not every space on the road is a double space and double spaces still can't accommodate all players (two at most, as the name implies).
As for who comes out first, if a player decides to occupy a double space on their turn, they're still the last player on the road, they still haven't leapfrogged at least one other player. Therefore, they get to go again. I don't see why this is problematic.
In any case, the manual is clear on this in both the language used and the illustrated examples: last in, first out, same as the Inn. I don't see where the confusion comes from.