What Happens if Fulfill is called Twice on a Promise

Question

This code is blocking the UI until the remote config fetch is done. I have put 2 seconds as timeout. Here both completionHandler and after will execute, whichever finishes first.

Will it be ok? Or do I need to take care that only one should execute?

func checkIfRemoteConfigFetched<T>(t:T) -> Promise<T>{
        return Promise<T>{ seal in

            if self.rConfig?.fetchComplete == true{
                seal.fulfill(t)
            }

            after(seconds: 2).done{
                seal.fulfill(t)
            }

            if let rConfig = self.rConfig{
                rConfig.completionHandler = { success in
                        seal.fulfill(t)
                }
            }
        }
    }