Had a similar issue with Strike Against Fugitive Support Network.
Got a critical success and it looked like it bundled another mission in with the reward. I received 566 Engineering XP, a double set of skill points, and an extra 5 dilitihium, all for no discernible reason.
So, what looks like it happening is it is treating you as if you received both a critical success and a standard success. Do either of you recall what it actually said before you accepted the reward?
The display had 2 sets of rewards end-to-end, including 2 listings of dilithium, and 2 listings of skill points and bridge officer skill points (and probably cxp). I'll try to remember to take a screenshot if it happens again.