how to pass two quries in UserManager in variable

var completedTask = await Task.WhenAny(_userManager.FindByNameAsync(userForLoginDto.UserName), _userManager.FindByIdAsync(userForLoginDto.Id)); 
var user = await completedTask; 
var result = await _signInManager.CheckPasswordSignInAsync(user, userForLoginDto.Password, false);

i found new error System.InvalidOperationException: A second operation started on this context before a previous operation completed.