Guard and Penetrate data disk.

In the past, we have had data disks that don't stack.  However, Guard and Penetrate appears to be different.

The text (for blue) states:

"At the start of (sic) battle units gain 300% Defense.  Whenever an ally is damaged by an enemy, they lose 10% of this Defense and gain 10 (sic) Defense Penetration.  Whenever an enemy is defeated, all allies gain 50% Defense.  (This effect doesn't stack)"

Now, it doesn't state (and I don't think from testing that) the whole disk doesn't stack.  So, am I to take it that these disks do indeed stack, other than what appears after the last full stop/period?  "Whenever an enemy is defeated, all allies gain 50% Defense.  (This effect doesn't stack)".

It seems a little odd that just this section doesn't stack.  50% after an enemy is defeated seems so little compared to the 300% when you start the battle.

Also, are they any worthwhile 1 dot data-disks in this Conquest?  They all seem quite useless, making matching 3 and 2 dot data-disks quite difficult.