Double entries in year

I've got a ridiculously stupid problem with double entries in my year tags, I don't know how come but some files have year\\year formatted tagfields. So I wanted to create a action which replaces that, looking like:

Replace: "YEAR": "%year%" -> "$num(%year%,4)"

Works fine when I choose only one file, but as soon as I've marked several files nothing changes.
Why is that?

Have you tried the action Remove duplicate fields?

Yes, I recognized that the year tags are written two times, but Remove duplicate fields didn't help neither.

It removes duplicate fields here. Can you please try with the current Development Build?

I have the same issue. I tried to use the "remove duplicates" action. My problem is that the last entry of the duplicates is the one I want to keep. For example for genre I have 4 listings: rock\\rock\\rock\\Classic Rock "Classic Rock is the one I want to keep.

Most of my songs have this issue with multiple tags and the last entry is the one that is right. I have this problem with all fields ....artist, title, album, and year.

It appears some of the tagging software I have used in the past didn't overwrite existing tags and just appended a new entry. I need to figure how to erase all entries but the newest. Now I have a mess. Any suggestion would be greatly appreciated. This task is very time consuming.