I was facing similar issue and wanted the gulp source to be copied to multiple locations after lint, uglify and minify tasks. I ended up resolving this as below,
gulp.task('script', function() {
return gulp.src(jsFilesSrc)
// lint command
// uglify and minify commands
.pipe(concat('all.min.js'))
.pipe(gulp.dest('build/js')) // <- Destination to one location
.pipe(gulp.dest('../../target/build/js')) // <- Destination to another location
});