No, Terra II was one of their own and they chose her to be an ambassador for Strata to the surface world. They mistakenly believed surgically altering her appearance to resemble one of their heroes would make it easier, but wasn't aware of Terra I's betrayal or history. The quixium element that gave Terra II her powers had the unforeseen side effect of wiping her memory, so when she showed up she was susceptible to suggestion. The genetic match that told Terra II she was the original Terra was also a side effect of the quixium.