I have take a bit more of a look at this, so ignore my previous post. The best way to acheive what you need is to remove the line:
$Daysold = Get-VM $GuestName | Get-Snapshot | Select @{N="DaysOld"; e={((Get-Date) - $_.Created).Days}}
Then because we are already retireving the created date for each snapshot to get the count of days since it was created as a propertie of the object all you need to to is change the line creating that property to:
$objReport | Add-Member -Type NoteProperty -Name "Days Old" -Value $((Get-Date) - $Snapshot.Created).Day
This should then create this property uniquely for each snapshot reported avaoiding the problem you are getting.
FYI, I am not near an environment I can test this on, so the syntax may be slightly off, but should point you in the right direction.
