Why is there no "backup duplication" item in Acronis True image 2021?

Question

Backup

Hello everyone, in ATI versions 2020 and 2021 it is not possible to do "backup copying", that is, if backup of files and folders is configured, then the "backup copy" item is in the parameters, but if backup of the entire disk is configured, then this item is not in the options. The documentation only states -

"This option is not available for backups that use Acronis Cloud as the destination, as well as for local backups created by Acronis True Image 2020 or later."

but it is not clear from this why, by making local backup copies of folders, I can duplicate these copies, but there are no copies of partitions. What am I doing wrong? Thank you.