Why the event receiver persist all the emitted values.how to listen to the most recent emitted value only

Question

as shown in the below posted code, i emit an event as shown in section emitting an event. the value to be emitted is a string and the log-statement confirm that as shown in the below posted screen-shot. the problem i am facing, is as i am registered to listen to the emitted event as shown in section ngOnInit below, i receive several values for the emitted value param as shown in the screen-shot.

in other words, assume that the event in emitting an event section is emitted on button clicks, for the first click

console.log("this.selectedSite.id:",this.selectedSite.id) displays 202207070658 which is the most recent emitted value. this line behave correctly as is displays the most recent value as expected

but the problem is in the ngOnInit section- For the first click "first emittance to the event",

console.log("******************selectedSiteID:",this.selectedSiteID) displays 202226081143
after clicking two times, it displays: 202226081143 and 202228011057
after clicking four time, it displays the values shown in the screen shot

i would like to receive only the most recent emitted value only. how can i achieve that

service:

export class FromSiteMapToVisOptionsService {
private broadcastEmitterToAckSelectedSiteID:Subject<string> = new ReplaySubject<string>();
constructor() { }

  public emitToAckSelectedSiteID(param) {
    this.broadcastEmitterToAckSelectedSiteID.next(param)
  }
  public getBroadcastEmitterToAckSelectedSiteID() {
    return this.broadcastEmitterToAckSelectedSiteID.asObservable()
  }
}

ngOnInit:

 this.subscriptionOnAckSelectedSiteID = this._FromSiteMapToVisOptionsService.getBroadcastEmitterToAckSelectedSiteID().subscribe((param:string)=>{
  this.selectedSiteID = param
  this.storedSelectedSiteID = this._PersistStateService.getItem(this.keySelectedSiteID)
  console.log("******************selectedSiteID:",this.selectedSiteID)
})

emitting an event

// assume it will be emitted on button clicks
this.subscriptionEventEmitterToRequestSelectedSiteID = this._FromVisOptionsToSiteMapService.getBroadcastEmitterToRequestSelectedSiteID().subscribe(()=> {
        console.log("this.selectedSite.id:",this.selectedSite.id)//displays the value of this.selectedSiteID only once.this.selectedSiteID contains only one value as shown in the screen-shot, its value is displayed once
        this._FromSiteMapToVisOptionsService.emitToAckSelectedSiteID(this.selectedSite.id)
    })

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