DOTNET Core migration problems

My ApplicationDbContext class

public class ApplicationDbContext : IdentityDbContext<User>
    {
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
            : base(options)
        { }
    }

first time when dotnet ef migrations add Intial it creates the identity tables in the cs file and running dotnet ef database update works fine.

After adding the following DbSet

public class ApplicationDbContext : IdentityDbContext<User>
    {
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
            : base(options)
        { }

        public DbSet<Book> Books { get; set; }
    }

dotnet ef migrations add Second works fine but running dotnet ef database update shows error.

Build started...Build succeeded.
fail: Microsoft.EntityFrameworkCore.Database.Command[20102]
      Failed executing DbCommand (16ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      CREATE TABLE "AspNetRoles" (
          "Id" text NOT NULL,
          "Name" character varying(256) NULL,
          "NormalizedName" character varying(256) NULL,
          "ConcurrencyStamp" text NULL,
          CONSTRAINT "PK_AspNetRoles" PRIMARY KEY ("Id")
      );
Failed executing DbCommand (16ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
CREATE TABLE "AspNetRoles" (
    "Id" text NOT NULL,
    "Name" character varying(256) NULL,
    "NormalizedName" character varying(256) NULL,
    "ConcurrencyStamp" text NULL,
    CONSTRAINT "PK_AspNetRoles" PRIMARY KEY ("Id")
);
Npgsql.PostgresException (0x80004005): 42P07: relation "AspNetRoles" already exists
   at Npgsql.NpgsqlConnector.<>c__DisplayClass160_0.<<DoReadMessage>g__ReadMessageLong|0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at Npgsql.NpgsqlConnector.<>c__DisplayClass160_0.<<DoReadMessage>g__ReadMessageLong|0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at Npgsql.NpgsqlDataReader.NextResult(Boolean async, Boolean isConsuming)
   at Npgsql.NpgsqlDataReader.NextResult()
   at Npgsql.NpgsqlCommand.ExecuteReaderAsync(CommandBehavior behavior, Boolean async, CancellationToken cancellationToken)
   at Npgsql.NpgsqlCommand.ExecuteNonQuery(Boolean async, CancellationToken cancellationToken)
   at Npgsql.NpgsqlCommand.ExecuteNonQuery()
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteNonQuery(RelationalCommandParameterObject parameterObject)
   at Microsoft.EntityFrameworkCore.Migrations.MigrationCommand.ExecuteNonQuery(IRelationalConnection connection, IReadOnlyDictionary`2 parameterValues)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationCommandExecutor.ExecuteNonQuery(IEnumerable`1 migrationCommands, IRelationalConnection connection)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase(String targetMigration, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabaseImpl(String targetMigration, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabase.<>c__DisplayClass0_0.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
  Exception data:
    Severity: ERROR
    SqlState: 42P07
    MessageText: relation "AspNetRoles" already exists
    File: heap.c
    Line: 1155
    Routine: heap_create_with_catalog
42P07: relation "AspNetRoles" already exists

Am I missing something or I need a separate DbContext class which I don't want?