In single apk can i use more than 1 banner with 1 unitId?

I have a application with a ads. And i have a 1 banner ads. Can i use same unit id for use more than 1 banner only ? Like if i want use 3 banner should i take 3 diffrent banner id or same is working well too ? I googled it but cant found any document or same question as i asked thats why i want to ask in here .If i can use then i will put two or three ads with same id. And is it effecting money to get ? I just need informations about it. Thanks for helps :)

secondBanner = BannerAd(       size: AdSize.banner,       adUnitId: "MyBannerId",       listener: BannerAdListener(onAdLoaded: (ad) {         setState(() {           secondBannerLoaded = true;         });         print("Banner AD LOADED!!!!!!!!!!!");       }, onAdFailedToLoad: (ad, error) {         print("Banner AD ERRRRRRRRRRRRRRRRRRRR!!!!!!!!!!!");         inspect(error);         ad.dispose();       }),       request: AdRequest(),     );     bannerAd = BannerAd(       size: AdSize.banner,       adUnitId: "MyBannerId",       listener: BannerAdListener(onAdLoaded: (ad) {         setState(() {           isLoaded = true;         });         print("Banner AD LOADED!!!!!!!!!!!");       }, onAdFailedToLoad: (ad, error) {         print("Banner AD ERRRRRRRRRRRRRRRRRRRR!!!!!!!!!!!");         inspect(error);         ad.dispose();       }),       request: AdRequest(),     );     bannerAd!.load();     secondBanner!.load();