More than one DbContext named 'myproject.Models.myprojectContext' was found. Specify which one to use by providing its fully qualified name using its exact case

I was developing a Web-Application in Asp.Net Core 2.2 . After I added the new identity with scaffold it generated me these codes:
For IdentityHostingStartup.cs

[assembly:
 HostingStartup(typeof(myproject.Areas.Identity.IdentityHostingStartup))]
namespace myproject.Areas.Identity
{
    public class IdentityHostingStartup : IHostingStartup
    {
     public void Configure(IWebHostBuilder builder)
      {
      builder.ConfigureServices((context, services) => {
      services.AddDbContext(options =>
       options.UseSqlServer(
       context.Configuration.GetConnectionString("myprojectContextConnection")));

        services.AddDefaultIdentity()
                .AddEntityFrameworkStores();
            });
        }
    }
}

Code in my Startup.cs (After adding Identity I made some modifications in startup.cs, with reference to this article)

public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. 
        //Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.Configure(options =>
            {
        // This lambda determines whether user consent for 
       //non-essential cookies is needed for a given request.
                options.CheckConsentNeeded = context => true;
                options.MinimumSameSitePolicy = SameSiteMode.None;
            });


 services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2)
.AddRazorPagesOptions(options =>
        {
        options.AllowAreas = true;
        options.Conventions.AuthorizeAreaFolder("Identity", "/Account/Manage");
        options.Conventions.AuthorizeAreaPage("Identity", "/Account/Logout");
        });

      services.ConfigureApplicationCookie(options =>
        {
        options.LoginPath = $"/Identity/Account/Login";
        options.LogoutPath = $"/Identity/Account/Logout";
        options.AccessDeniedPath = $"/Identity/Account/AccessDenied";
        });

        services.Configure(Configuration.GetSection("EmailSettings"));
        services.AddSingleton();
        services.AddScoped();

        }

        // This method gets called by the runtime. 
       //Use this method to configure the HTTP request pipeline.
 public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseStaticFiles();
            app.UseCookiePolicy();
            app.UseAuthentication();
            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }

This was working fine, then I added new models and wanted to scaffold a model with controller and views using Entity Framework. After I set up everything and click ok, I started getting error saying : More than one DbContext named 'myproject.Models.myprojectContext' was found. Specify which one to use by providing its fully qualified name using its exact case.

 To resolve this issue I removed following lines of code from IdentityHostingStartup.cs

  services.AddDbContext(options =>
   options.UseSqlServer(
   context.Configuration.GetConnectionString("myprojectContextConnection")));

And I modified my startup.cs file to following

 public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. 
        //Use this method to add services to the container.
 public void ConfigureServices(IServiceCollection services)
   {
    services.Configure(options =>
      {
      // This lambda determines whether user consent for 
      //non-essential cookies is needed for a given request.
       options.CheckConsentNeeded = context => true;
       options.MinimumSameSitePolicy = SameSiteMode.None;
      });

  services.AddDbContext(options =>
  options.UseSqlServer(Configuration
.GetConnectionString("myprojectContextConnection")));


  services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2)
.AddRazorPagesOptions(options =>
    {
    options.AllowAreas = true;
    options.Conventions.AuthorizeAreaFolder("Identity", "/Account/Manage");
    options.Conventions.AuthorizeAreaPage("Identity", "/Account/Logout");
     });

   services.ConfigureApplicationCookie(options =>
    {
    options.LoginPath = $"/Identity/Account/Login";
    options.LogoutPath = $"/Identity/Account/Logout";
    options.AccessDeniedPath = $"/Identity/Account/AccessDenied";
     });

    services.Configure(Configuration.GetSection("EmailSettings"));
    services.AddSingleton();
    services.AddScoped();

    }

        // This method gets called by the runtime. 
        //Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change 
                //this for production scenarios,
                // see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseStaticFiles();
            app.UseCookiePolicy();
            app.UseAuthentication();
            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }

Now I try generating Scaffold items it works without any error.