Testing your code:
\\\ \\@ \@\ \@@ @\\ @\@ @@\ @@@ \\ \@ @\ @@ \ @
DC2\ DC2@ DC1\ DC1@ DC2\ DC2@ DC1\ DC1@ DC2 DC1 DC2 DC1 \ @
Testing simultaneous replacements:
\\\ \\@ \@\ \@@ @\\ @\@ @@\ @@@ \\ \@ @\ @@ \ @
DC2\ DC2@ DC1\ DC1@ DC2\ DC2@ DC1\ DC1@ DC2 DC1 DC2 DC1 \ @