fix: replication regression due to proxying requests (#11356)

In PR #11165 due to incorrect proxying for 2 
way replication even when the object was not 
yet replicated

Additionally, fix metadata comparisons when
deciding to do full replication vs metadata copy.

fixes #11340

cmd/object-api-options.go

@@ -66,7 +66,10 @@ func getDefaultOpts(header http.Header, copySource bool, metadata map[string]str
 	if crypto.S3.IsRequested(header) || (metadata != nil && crypto.S3.IsEncrypted(metadata)) {
 		opts.ServerSideEncryption = encrypt.NewSSE()
 	}
-	opts.ProxyRequest = header.Get(xhttp.MinIOSourceProxyRequest) == "true"
+	if v, ok := header[xhttp.MinIOSourceProxyRequest]; ok {
+		opts.ProxyHeaderSet = true
+		opts.ProxyRequest = strings.Join(v, "") == "true"
+	}
 	return
 }