Problem about “tow guys play a game on one device“

So the device must response to their touches、movings、and draggings in the sametime. Take the “void ccTouchMoved(CCTouch* touch, CCEvent* event)” fuction as an example, can this function identify whoes moving is it? Here is my code, I tested it on an android phone and it worked bad. The two Fixtures’ moving may effect eath other.
void HelloWorld::ccTouchMoved(CCTouch* touch, CCEvent* event)
{
CCPoint touchLocation = touch~~>locationInView );
touchLocation = CCDirector::sharedDirector~~>convertToGL;
CCPoint nodePosition = convertToNodeSpace;
m_mouseWorld = b2Vec2;
if )
{
if
{
m_mouseJoint1~~>SetTarget;
}
}
if )
{
if
{
m_mouseJoint2~~>SetTarget(m_mouseWorld);
}
}
}

Take a look: http://www.gmtdev.com/blog/2011/12/06/multi-touch-in-cocos2d-x/