How to replace class with alternative sourceSet with Kotlin Multiplatform

Question

I am trying to make replacement of "expect fun A()" that have implementation in androidSourceSet with another implementation in mockSourceSet by using the android build flavor.

Structure of my project is

Android:App:
   installed:
    src
      androidTest:
      main:
        <class App()>
      mock:
        <class App()>(there it works)
   instant:...
Shared:
   core:
      src
         androidMain
            <actual fun A()>
         androidMock
            <actual fun A()>(to replace)
         commonMain
         iosMain

there is shared:core buildscript:

android {
    compileSdk = Versions.compileSdk
    defaultConfig {
        minSdk = Versions.minSdk
    }

    flavorDimensions += "version"
    productFlavors {
        create("prod") {
            dimension = "version"
        }
        create("mock") {
            dimension = "version"
        }
    }
}
kotlin {
    androidTarget()

    iosX64()
    iosArm64()
    iosSimulatorArm64()

    sourceSets {
        commonMain.dependencies {
            ...
        }

        androidMain.dependencies {
            ...
        }

        iosMain.dependencies {
            ...
        }

        val androidMock by sourceSets.creating {
            dependsOn(androidMain.get())
        }
    }
}

But i get error "Conflicting overloads: public actual fun A()" What approach i can use to have mock code organized and avoid if(buildType.value) blocks in production code?