How to find double coins in collections

For example, in my collection based on the info below I understand that 1 coins is doubled. But how to find which one was entered into collection twice.  Is there any way to find out this fast, but not checking each of thousands coins.

6741 Coins

6740 Different coins

Dear Numista Experts, give me advice !

This could be a room for improvement (probably it is already implemented)

Thanks in advance,

afpcoins

Hello.  I answered this question a while back.  https://en.numista.com/forum/topic112026.html

Let me know if you need additional explanation. 

rsirian1

Hello.  I answered this question a while back.  https://en.numista.com/forum/topic112026.html

 

Let me know if you need additional explanation. 

Thanks Rsiriran1! 

It really helped me to find 1 double (due to changes in Numista catalog - 2 coins profiles have been unified into one recently… that lead to 1 double coins in my collection ). 

Hello rsirian1,

I have a difference of 13 coins between Coins (19,931) and Different Coins (19,918). I ran the spreadsheet following the instructions and formula that you provided. It located supposed duplicates (with the number 3) but in my case they were actually different varieties of the same date, N#, etc. I stopped counting after 20 occurrences because I realized there were going to be hundreds of examples.

Before exporting the file there is a Version list with an option to choose "Comments". These comments explain the different varieties: large letters, small letters, signature, no signature, different mint locations, etc.  

SRV5490

Hello rsirian1,

 

 

Hello.  You're correct. If there are varieties on the same coin, year, mint mark then you need to add the comments to the export and the first cell becomes:

=(C2=C3) + (E2=E3) + (F2=F3) + (G2=G3)

if the comments are in column G.  Look for the 4's.