if I implement two different admob account, ad unit id in one app then any risk on my admob account
Yes, you could use multiple Admob accounts ads in your one App.
But you should be prepared of the following things :
- Your Ads RPM would get down as for same inventory Two Ads platform are bidding. hence the lowest value.
- Your income would drastically get down, as Two Ad platforms means lowest bid value. Low CPC and Low Ad impression for one Ad Platform.