You must also remember that the peanut bars also contain around 40cals more than the sachets/tetras, so, by having 3 a day you'd be adding an extra 120cals to the diet.
Carb/ketosis-wise it is fine to have both of the 'crunch' bars 3 times per day. As i've said though, you'll incur extra calories (incidentally, the cranberry bars only contain 20cals more than the sachets), and, as Mike says, the amount of fibre can cause a windy or upset tummy. On the other hand, if the peanut bars are really the only thing you can stomach (and your stomach isn't upset by them!), then 3 bars a day is better than not doing the diet at all.
On a side note, this advice is not applicable to the other four flavoured bars, as they're too high in carbs to have more than one per day!
Jo x