One way is to go to the card page itself and look under "Mentions" and expand "Collections". Find your ID and see how many are listed as in your collections. If the number is more than you thought in the one collection, you will know that there is another in a different collection. Which collection is then a matter of going through all your collections to find where it is at.
Bruno
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Check my Profile page to see my 2023 Goals and my Lists of sets near completion (5 cards or less) or sets getting close (less than 100 cards missing and 75% complete).
https://www.tcdb.com/Forum.cfm/Page/B/ID/0/?MODE=VIEW&ThreadID=25745&C=0