How to make robocopy overwrite files?

Question

I cannot make robocopy overwrite files.

I need to get copy speed stats on one big file but the file to copy is skipped once already copied :

PS C:\> ls ~/Downloads/19041.1.191206-1406.vb_release_CLIENTLANGPACKDVD_OEM_MULTI.iso | % { $_.length/1GB }
5.54226303100586
PS C:\> robocopy $HOME\Downloads $destDIR 19041.1.191206-1406.vb_release_CLIENTLANGPACKDVD_OEM_MULTI.iso /IS
.....
               Total    Copied   Skipped  Mismatch    FAILED    Extras
    Dirs :         1         0         1         0         0         0
   Files :         1         0         1         0         0         0
   Bytes :   5.542 g         0   5.542 g         0         0         0
   Times :   0:00:00   0:00:00                       0:00:00   0:00:00
   Ended : Thursday, April 11, 2024 11:38:38 AM

I tried the answers/comments found here , there and there so I tried adding /IT /TS /FP /V /R:0 /NODCOPY at the end of the robocopy command line but I get the same result :

PS C:\> robocopy $HOME\Downloads $destDIR 19041.1.191206-1406.vb_release_CLIENTLANGPACKDVD_OEM_MULTI.iso /IS /IT /TS /FP /V /R:0 /NODCOPY
               Total    Copied   Skipped  Mismatch    FAILED    Extras
    Dirs :         1         0         1         0         0         0
   Files :         1         0         1         0         0         0
   Bytes :   5.542 g         0   5.542 g         0         0         0
   Times :   0:00:00   0:00:00                       0:00:00   0:00:00
   Ended : Thursday, April 11, 2024 11:40:24 AM