Remote Event Receiver(existing) stops working when a new remote event receiver is added

I’m not sure what’s going wrong, hoping someone to correct me here. I have an itemadding RER which works well and smooth, the problem occurs when i add one more to the tenant. The Second RER actually starts working after the deploy and the first RER(existing) actually stops responding. May i know why is this happening? Btw, i’m using different client ID and client secret for both the app.