how to resolve messagingcenter.subscribe calling multiple times in xamarin.forms

Question

MessagingCenter.Subscribe calling multile times but i called MessagingCenter.send only one time.how to resolve this issue.

I'm subscribe from model's constructor

 MessagingCenter.Subscribe<App, List<string>>(this, "hi", async (arg1, list) =>
        { //code });

calling send in android's renderer

Xamarin.Forms.MessagingCenter.Send<App, List<string>>((App)Xamarin.Forms.Application.Current, "hi", list);