NewNPC always contains Marketboard and Summoning Bell

I found that NewNPC always contains Marketboard and Summoning Bell.
This problem always occurs when the character is near the market.

Code:

ActorReadResult readResult = Reader.GetActors();
foreach (var id in readResult.NewNPC)
{
    string strNPC = "NPC => ID: " + id + ", Name: " + readResult.NPCEntities[id].Name;
    Console.WriteLine(strNPC);
}

Result:

NPC => ID: 2000402, Name: マーケットボード
NPC => ID: 2000401, Name: 呼び鈴
NPC => ID: 2000402, Name: マーケットボード

Remarks:
"Marketbord" is "マーケットボード" in Japanese.
"Summoning Bell" is "呼び鈴" in Japanese.

ActorReadResult.RemovedNPC type is Dictonary disallowing duplicate keys.
But ActorReadResult.NewNPC type is List allowing duplicate values.

This issue may occur if an object with the same key exists in memory.