I\'m having troubles in accessing both (front and rear cameras at the same time). When turn on one camera it works. When i turn off first and turn on second it works. It g
This question basically says it cannot be done, but there may be some hack. This lack of response from google groups tells me most likely not. Here is another no-response post on google groups. Here is another post discussing the use of two cameras at the same time.
So my initial answer is no, it is not possible. BUT there may be some workaround, you just may have to find it yourself because it isn't discovered yet :).
EDIT 11/21/11: Unfortunately I found even further proof that it cannot be done, official from Sprint/HTC here. I realize you are using a Sensation, and this is an EVO 4g, but I'm sure it still applies.