yea i dont know how to explain my question. what im saying is isnt stereo tracks from keyboards or vst instruments just hard left and right not panned left or right?
First, understand what panning is. Stereo channels are a relatively new invention. Well after we had stereo records, we still had mixers with only mono channels, and multi-track recorders with only mono tracks. If it was a stereo mixer it had a stereo buss. If it had a stereo buss, it had pan pots to assign how much of each track got sent to the left channel of the stereo buss, and how much of it goes to the right channel of the stereo buss (and by extension, how much ends up in the left speaker, and how much in the right speaker). With tha pan centered, the channel was routed with even amounts going to the left and right buss wire (yes, it was actually a pair of buss wires running horizontally across the mixer). A pan pot (potentiometer) had the channel output going to the center (wiper) and the two ends going to the left and right buss. Turning the pot from center would simultainously increase the resistance to one buss, while decreasing the resistance to the other buss.
Ok, back to the future. Even before we got software mixers, we got stereo channels on analog mixers, usually with only line inputs. The left and right outputs of synths, drum machines, etc., could be controlled by a single channel. These channels use stacked pots to control 2 channels at one time. When the signal reaches the pan pot, the stacked pot is wired with each of the two signals (L&R) going to one of the two wipers. The two halves of the stereo buss are wired one to the CW terminal of the upper pot, the other to the CCW terminal of the lower pot. So, when you turn the pan knob, you are no longer really panning in the mono sense. You are now turning up the volume of one half the stereo signal as it routes to it's buss, while simultaniously turning down the other half. Most pan pots have their tapers such that in the center position, the signal on each side is down by 3dB so that the relative loudness remains consistant as you pan, and not louder when both left and right are equal. This is one version of "pan law".
Once we get into software mixers and recorders, we can do anything wth code. So we have stereo tracks, which are really two mono tracks that are linked by code, and stereo channels, again virtual mono channels linked by code. Since they really are seperate, good software will allow you to make and break that link anytime you want. The link is just a code representation of the stacked pots. When you convert to dual mono channels, it's like unplugging from an analog stereo channel with it's stacked pots, and plugging into two adjacent mono channels. This allows you to do different things with panning, like adjusting the width.
At least, this is how it works with the gear and programs I'm familiar with. Can't say it holds for any and all cases.