As I said, AB, it is an interesting point and the CPS guideline is enlightening.
I think in practical terms if Magistrates were presented with a defendant facing two charges they would have to consider the "totality" of the offences and in many cases I would suggest that they would determine that they arose from a single "event". If they did decide to sentence separately they may impose two fines but if they decided the offences were too serious for a fine any community order or custodial sentence would certainly be concurrent. As with all multiple traffic offences penalty points or a disqualification would only be imposed for the most seriou, although the licence would be endorsed with the details of both offences.
An interesting topic. It would be useful to see any case law on the matter but I cannot find any immediately.