awk '{sub(/are hello/,"are are")sub(/you hello/,"you you")}1' file
/foo/bar/how /SOME_TEXT_HERE/hello
/foo/bar/are are/SOME_OTHER_TEXT
/foo/bar/you you
awk '{sub(/are hello/,"are are")sub(/you hello/,"you you")}1' file
/foo/bar/how /SOME_TEXT_HERE/hello
/foo/bar/are are/SOME_OTHER_TEXT
/foo/bar/you you