Just in case helpful this is what we use to mirror-copy the backup files to A.N.Other server (offsite obviously better than on-site, but on-site elsewhere is a 2nd-best choice and better than no-mirror IMHO)
ROBOCOPY s:\BackupFileSourcePath \\RemoteServer\RemoteShare\Remotepath *.BAK
/MIR /MT:8 /R:4 /W:10 /TEE /LOG+:c:\LogFilePath\RoboMirror.LOG
That then needs scheduling regularly (as often as the most frequent backup interval), and then something else needs to check that it is actually working, i.e.
contains a file that is "recent", although a test that it contains ALL files would also guard against largest files exceeding disk space
(That doesn't have to be a share, it could be a mapped drive, but Mapped Drive is probably more "fragile")
And then something, else, needs to cycle/purge the Error and Log files (which are created Belt & Braces just in case they need reviewing if/when something bad happens ...
But maybe there are better / smarter ways of doing the same?