Sorry to hear that random moved-ins derailed your plan for the two dreamies. -__-
If you got your unwanted new villagers via wifi trading or streetpass, 
perhaps next time when you have any open slots, you would consider putting the town in 'lockdown mode' until you have securely invited the ones you wanted, and see their plots up. (meaning:no wifi trades, no one comes in/goes out, and you don't travel to other towns UNLESS it's to the towns where you wanted to invite your desired villagers in) 
In case you are interested in more details on how to safely TT someone out, 
and more info regarding villagers' moving rumors:
http://www.belltreeforums.com/showthread.php?82107-Guide-Fool-Proof-Guide-to-Moving-Villagers-OUT
http://www.belltreeforums.com/showthread.php?145364-Villager-Moving-Rumors-(guide)
Good luck & have fun! C: