powershell array of object with dynamic properties outputs only properties from first element

Question

why ? and how to fix this ? how to export to csv file now after export i receive the same as when displaying $res.

$res= @()
$obj = [PSCustomObject]@{}
$obj | Add-Member -MemberType NoteProperty -Name "name1" -Value "value1"
$res += $obj
$obj = [PSCustomObject]@{}
$obj | Add-Member -MemberType NoteProperty -Name "name2" -Value "value2"
$res += $obj
$res


<#
received result

name1
-----
value1

#expected result 

name1  name2 
-----  ----- 
value1 
       value2


#>