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I haven't looked at my collection in over 20 years but back in '93 I went to buy a copy of X-Men #25 and noticed that one of them had the Gambit hologram printed upside down. Of course, knowing that it was an error I bought it. I have only heard of one other guy in NY having a similar copy-the hologram isn't blue and isn't black-just printed upside down. How would I go about getting a value for it?