Oh and Merry Christmas to you all too. 
read about half the comments -
gift card or not - if you were trying to be ‘thoughtful’, being second in line with it looks like you ‘followed along’ and doesn’t show the reciever that you actually thought of it yourself (which, if something they would truly be interested in, shows that you’ve been paying attention to them).
I’d be pissed, simply becuase it steals ‘my intentions’ - not wether or not duplicates are welcomed - or if the other person thought - “hey, great idea”.
IMHO, you were trying to make an impression on your prospective MIL - you found (of your own accord) something they would like - your fiance, by buying the exact same thing - takes that impression and makes it seem like you only thought of it becuase they did, which isnt the case.
on edit - finished reading other comments - nice that she apologized and you all worked it out … merry christmas and all that.
That sounds about right to me.
Can I just say, that I find it remarkable that so many folks would flat out tell him to cancel the engagement over this. We know so little about both these people and their relationship apart from this incident. To flat out tell him to look for someone else is ridiculous and appalling.
I think to make up for the error Tab A should be insirted in to Slot B.
This was a blessing for you.
Take all the money you were going to use for moving expenses and buy the MIL the most magnificent gift you can find.
You believe she not giving her mother a christmas gift on christmas? “oh Mom we have to wait for the special arrival tommorrow!”
You may already be a write off in their eyes.
As an aside I can’t believe between the two of you, you couldn’t come up with a better idea than a gift card!
I agree. With the caveat that, perhaps it ISN’T a big deal, and in the scheme of things, not important; however, at this stage of the game, and given the circumstances, it IS in fact indicative of what sort of a person fiancee is.
Furthermore, I’m still not getting the whole “give her separate gifts” thing; as Shayna suggested, why doesn’t fiance put your name on the card [or whatever] too? Or present it to her mother and say “This is from Idle and I; it was really his idea though, and wouldn’t rest until we got you this.” You’re on the same frigging side, for heaven’s sake; you’re essentially the same family unit, at this point [assuming you’re formally engaged and not one of these half-hearted wish you were engaged situations] and should be giving family gifts jointly. The fact that your not rings very strangely to my ears.
A combination of her actions and, more significantly, her response to the fact that she upset him. It suggests a lack of respect. Hopefully this was a very isolated one.
Utterly brilliant!
Sailboat