Vault 101 was a copy of Vault 13's experiment. Vault 13 was to stay closed for 200 years to study prolonged isolation. Vault 101 pretty much the samething but it was to never open. Two vaults with the same experiment, get going beth :thumbsup:
Vault 101 was designed primarily to see how long a group could stay in isolation. As in Vault tec was hoping for results of 1000 years plus to gather data for long term space voyages. Vault 13's mission was to study prolonged isolation but cleary another goal (if not the main one) was to recolonize (3 GECKS were given to it) and therefore was more of a "control" vault than a true "experiment" vault.
Vault 101s populace was apparently never intented to recolonize (lack of a GECK) and was just supposed to stay there as long as they could under an absolutely powerful overseer (which the scientists hoped would be a very long time, longer than Vault 13 anyway, a lack of a GECK would motivate them to stay longer).
Makes sense to also have two "long term isolation experiments" going when that would be one of your primary concerns (space voyage was a goal in mind). Having 1 man and 999 women, for instance, was kind of a "ehh...lets try it once" kinda thing.
I don't think Beth messed up at all with 101. I thought it made sense. :shrug: