@ng772 - The extra information you pass should be unique to each call. If you call two DCRs in rapid succession, and each DCR has a unique payload (event.detail), the values available to each DCR will come from their respective payload, setting the correct (expected) values.
For your last question, anything passed in as the second argument in the _satellite.track() call will be accessible to you inside the DCR. Consider the example below:
var payload = {
make: "Honda",
model: "Civic",
color: "Purple"
}
_satellite.track("getCarInfo", payload);
In the DCR, you would be able to specify event.detail.make, event.detail.model, and event.detail.color to gather the car information and map to props/eVars/etc.
If you're asking if it's possible to collect/build a history of everything passed in over the course of several calls to _satellite.track(), that's a solution you'd have to custom build.