She had merely copied Chi Mu's method of setting her up, digging a similar trap for her. The design drafts Fan Ming saw in her computer were not her real ones, which she had willingly let them steal.
She did this firstly to protect herself, secondly to set a trap for Chi Mu. But she never expected that Chi Mu would actually succumb to her desire to win and fall into the trap she had dug, even using the deceptive design draft she and Fan Ming had stolen...
She had managed to trick Chi Mu, but ultimately, she didn't stoop to the same underhanded level as Fan Ming, who had switched her USB. She simply couldn't resort to such base methods.