LIVETEXTURE FRONT CAMERA BACK, STOP VUFORIA PLUGIN

i've been trying to put the two cameras working on the same time, back camera using one Vuforia Image Target plugin and the other one prime31 Livetexture Plugin.

but when the texture starts to work the other camera stops. and the line that make the problem is this one:

texture = LiveTextureBinding.startCameraCapture( true, LTCapturePreset.Size640x480 );