deduplicate warning while copying

Signed-off-by: Billy Zha <[email protected]>

cmd/oras/internal/option/remote.go

@@ -67,6 +67,7 @@ func (opts *Remote) EnableDistributionSpecFlag() {
 func (opts *Remote) ApplyFlags(fs *pflag.FlagSet) {
 	opts.ApplyFlagsWithPrefix(fs, "", "")
 	fs.BoolVarP(&opts.PasswordFromStdin, "password-stdin", "", false, "read password or identity token from stdin")
+	opts.warned = &sync.Map{}
 }
 
 func applyPrefix(prefix, description string) (flagPrefix, notePrefix string) {
@@ -107,7 +108,6 @@ func (opts *Remote) ApplyFlagsWithPrefix(fs *pflag.FlagSet, prefix, description
 
 // Parse tries to read password with optional cmd prompt.
 func (opts *Remote) Parse() error {
-	opts.warned = &sync.Map{}
 	if err := opts.parseCustomHeaders(); err != nil {
 		return err
 	}

cmd/oras/internal/option/target.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"os"
 	"strings"
+	"sync"
 
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/pflag"
@@ -200,6 +201,8 @@ func (opts *BinaryTarget) ApplyFlags(fs *pflag.FlagSet) {
 	opts.From.ApplyFlagsWithPrefix(fs, "from", "source")
 	opts.To.ApplyFlagsWithPrefix(fs, "to", "destination")
 	fs.StringArrayVarP(&opts.resolveFlag, "resolve", "", nil, "base DNS rules formatted in `host:port:address[:address_port]` for --from-resolve and --to-resolve")
+	opts.From.warned = &sync.Map{}
+	opts.To.warned = opts.From.warned
 }
 
 // Parse parses user-provided flags and arguments into option struct.