Backup from same disk on linux and windows

So I’m in the process of moving from win11 to manjaro. I am going to run a computer with dualboot so I will keep my old win11 in case the manjaro completely fails somehow, never used arch linux before so I’d rather keep it safe for a year or so.

The backup location of my urbackup server is in btrfs.

So one of the disks I’m backing up (only using incremental backups, no image backups) on my win11 is also mounted in manjaro, but since it’s used in win11 I have to keep it ntfs for now.

So my question is, if I backup from manjaro, the files are obv the same but since it’s ntfs, i have to decide what user and group to mount it as and then all files and directories gets that owner/group/permission.
How will urbackup handle this? The disk is about 2tb of files, and I’d rather not the same files occupy 4tb. I know it works with multiple windows clients, when urbackup runs the daily cleanup the reported “statistics” drops, ie urbackup understands the files are exactly the same.
Devs, please advice.