Q: Itunes - Id3 - ***** !!

1. If you want your library to be identical in two or more locations, you need to replicate the complete library, not just the media.
2. To ensure that your metadata values are persistent, you need to turn off all functions that access Apple's servers and may modify your library content (Apple Music, Match, iCloud ...).
3. iTunes uses a hybrid metadata scheme, combining the elements stored within media files with those held within its own database.  Modifying elements in the media files may result in inconsistencies that, unfortunately, iTunes doesn't deal with very well.

I realize English may not be your main language but it is very hard to understand what it is you are trying to accomplish. "Reproductor" is not an English word.

Deleting tags is the worst way to keep your library organized.

If suspect that Orwellforfai is referring to the situation where a file contains duplicated/redundant tags based on different ID3 versions, which the iTunes Convert ID Tags ... function may help to resolve.  In general, use of 3rd party taggers in conjunction with iTunes does not work well, though doing so to clean up metadata elements and values before adding media to iTunes is OK.  Once media is in the iTunes library, however, I'd suggest using iTunes - and only iTunes - to make any subsequent changes.

In many cases changes made by third party taggers won't be visible in iTunes until you actually play the relevant songs.  Almost everything you see in the iTunes user interface is based on the information held in its database, based on the assumption that this is consistent with the metadata held in the media files.  In most cases iTunes will only compare (and, if necessary, update) the database information when it actually needs to access a media file (play or sync operations).

To replicate your library:

• Make sure that the complete library is in a consistent structure under one parent folder, like this:
  
• If necessary, use iTunes Consolidate Library function to copy any media that is in locations outside the iTunes Media folder structure into it.  See turingtest2's user tip on Make a split library portable for more info on steps that may be necessary to bring your library into this layout.
• Copy the complete iTunes folder from old computer to new ... depending on the size of the library, you can copy over a network, with a flash drive or with an external hard drive.
• Then either:
  • copy the iTunes folder from the 1st computer to the existing library location (this will overwrite existing content, so you may need to take steps to re-add any media that's on the 2nd machine but not on the 1st)
  • copy the iTunes folder from the 1st computer to a different library location, then SHIFT-start iTunes and select the iTunes Library.itl file in the folder you just copied

See How to move your iTunes library to a new computer - Apple Support for more info.