.Net Core and project.lock.json

Question

I have a VS2015 (Update 3) solution with several projects: one ASP.Net Core website and several .Net Core class libraries. Every time I add a reference from one project to another, I get reference error on one or more projects:

If I look at the Error List as the error message on References suggests, I see the following error for every project whose references broke: "An item with the same key has already been added. Key: Ansarada.ServicesApi.ApplicationServices".

To fix the issue, I delete project.lock.json for each broken project. VS straight away regenerates it, and then the project is fixed. This is obviously very annoying. Any solutions to this? Thanks.

---

Addition to the original question. I have been asked to provide my project.json files. Here are files for 3 projects (there are more in the whole solution):

Ansarada.ServicesApi.ServiceHost project.json:

{
    "dependencies": {
        "Ansarada.ServicesApi.Settings": "1.0.0-*",
        "Ansarada.ServicesApi.DependencyInjection": "1.0.0-*",
        "Ansarada.ServicesApi.Middleware": "1.0.0-*",
        "Autofac.Extensions.DependencyInjection": "4.0.0",
        "Microsoft.AspNetCore.Routing": "1.1.0",
        "Microsoft.AspNetCore.Server.IISIntegration": "1.1.0",
        "Microsoft.AspNetCore.Server.Kestrel": "1.1.0",
        "Microsoft.AspNetCore.Mvc": "1.1.1",
        "Ansarada.ServicesApi.ApplicationServices": "1.0.0-*",
        "Ansarada.ServicesApi.Enums": "1.0.0-*"
    },

    "tools": {
        "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final"
    },

    "frameworks": {
        "net462": {}
    },

    "buildOptions": {
        "emitEntryPoint": true,
        "preserveCompilationContext": true
    },

    "runtimeOptions": {
        "configProperties": {
            "System.GC.Server": true
        }
    },

    "publishOptions": {
        "include": [
            "wwwroot",
            "**/*.cshtml",
            "appsettings*.json",
            "web.config"
        ]
    },

    "scripts": {
        "postpublish": ["dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%"]
    }
}

Ansarada.ServicesApi.ApplicationServices project.json:

{
    "version": "1.0.0-*",
   "frameworks": {
      "net462": {}
   },
   "dependencies": {
      "Ansarada.ServicesApi.Enums": "1.0.0-*",
      "Ansarada.ServicesApi.Proxies": "1.0.0-*",
      "Ansarada.ServicesApi.Repositories": "1.0.0-*"
   }
}

Ansarada.ServicesApi.Repositories project.json:

{
    "version": "1.0.0-*",
   "frameworks": {
      "net462": {
         "frameworkAssemblies": {
            "System.Transactions": "4.0.0.0"
         }
      }
   },
   "dependencies": {
      "Ansarada.ServicesApi.Enums": "1.0.0-*",
      "Ansarada.ServicesApi.Settings": "1.0.0-*",
      "Dapper": "1.50.2"
   }
}