error CS0757: A partial method may not have multiple implementing declarations

[KeNJiKunG]

Please do the checklist before filing an issue:

• I have read the documentation, including the FAQ
• I can reproduce the bug using the latest prerelease version
• I have searched existing discussion and issue to avoid duplicates

Describe the bug
Compiler ends with error CS0757. I have tried with .NET 9, 8 but errors still occurred. The generated codes is correct and have only 1 file. It gone after I set PrivateAssets="all".

Declaration code

#:package Riok.Mapperly@4.3.1

using Riok.Mapperly.Abstractions;

namespace Test;

public class Class1
{
    public int a { get; set; }
}

public class Class2
{
    public int a { get; set; }
}

[Mapper]
public static partial class Mapper
{
    public static partial Class1 To1( Class2 class2 );
}

Environment (please complete the following information):

• Mapperly Version: [e.g. 4.3.1]
• Nullable reference types: [e.g. enabled]
• .NET Version: [e.g. .NET 10.0.200--preview.0.26103.119]
• Target Framework: [e.g. .net10.0]
• IDE: [e.g. Visual Studio Code]
• OS: [e.g. Windows 11]

Additional context
Add any other context about the problem here.

[latonz]

Does it work if you build it on the console? Does it work in another IDE?