setdate()
{
  # set file $1 to have same timestamp as file $2
  touch -t $(date -r "$2" "+%Y%m%d%H%M.%S") "$1"
}

$ ls -ltTr
$ ls -ltTr;
total 10
-rw-------  1 jim  jim  405 Jul 22 14:12:52 2019 foo
-rw-------  1 jim  jim  361 Jul 22 14:13:06 2019 bar
-rw-------  1 jim  jim    0 Jul 22 16:17:06 2019 farkle
$ setdate farkle bar # sets timestamp of file 'farkle' to be the same as 'bar'
$ ls -ltTr;
total 10
-rw-------  1 jim  jim  405 Jul 22 14:12:52 2019 foo
-rw-------  1 jim  jim    0 Jul 22 14:13:06 2019 farkle
-rw-------  1 jim  jim  361 Jul 22 14:13:06 2019 bar

$ mkdir backup
$ cp -p *.mp4 backup/

$ for i in *.mp4; do setdate "$i" "backup/$i"; done