Please use override option or check for definition, koin android?

I am implementing Koin DI in my android application. I was successfully able to create some of the modules. However I got an exception where I tried to get object from another in module.

These are my modules

val networkModule = module {
factory { provideRetrofit() }

single { provideNetworkApi(get()) }
}


fun provideRetrofit(): Retrofit {
return Retrofit.Builder()
    .baseUrl(NetworkConstant.BASE_URL)
    .addConverterFactory(
        GsonConverterFactory.create(
            GsonBuilder().setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
                .create()
        )
    )
    .client(OkHttpClient.Builder().build())
    .build()

 }

fun provideNetworkApi(retrofit: Retrofit): NetworkCall =
retrofit.create(NetworkCall::class.java)

view model module - i want to pass the network call object here

val viewModelModule = module {
single { provideNetworkApi(get ()) }
}

This is my code in application class

startKoin {
        androidLogger()
        androidContext(this@BaseApp)
        modules(listOf(networkModule,viewModelModule))
    }

This is the exception I get

java.lang.RuntimeException: Unable to create application com.mountmeru.BaseApp: org.koin.core.error.DefinitionOverrideException: Definition '[Factory:'com.mountmeru.network.NetworkCall']' try to override existing definition. Please use override option or check for definition '[Factory:'com.mountmeru.network.NetworkCall']'
    at android.app.ActivityThread.handleBindApplication(ActivityThread.java:6465)
    at android.app.ActivityThread.access$1300(ActivityThread.java:219)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1859)
    at android.os.Handler.dispatchMessage(Handler.java:107)
    at android.os.Looper.loop(Looper.java:214)
    at android.app.ActivityThread.main(ActivityThread.java:7356)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
 Caused by: org.koin.core.error.DefinitionOverrideException: Definition '[Factory:'com.mountmeru.network.NetworkCall']' try to override existing definition. Please use override option or check for definition '[Factory:'com.mountmeru.network.NetworkCall']'
    at org.koin.core.scope.ScopeDefinition.save(ScopeDefinition.kt:25)

Any clue whats wrong here?

I was doing it all wrong. The correct implementation is

I wanted the NetworkCall object in my LoginViewModel

val viewModelModule = module {
single { LoginViewModel(get()) }
}

And the viewmodel class is follows

class LoginViewModel(val networkCall: NetworkCall) : ViewModel(){

}

So far I feel koin is quite good