Getting several duplicates (usually two) of incoming messages in Outlook Express. Have Windows XP operating system.

Off hand, this sounds like you have multiple duplicate accounts setup in OE (Outlook Express).
Open OE. At the top, select Tools > Accounts.
Depending on what version of OE, there should be an tab or option for Email. If there are several listed, that could explain the duplicate emails. If the accounts are the same name, but differentiated by a number, that would be the duplicate email. Select the account with the number and there is an option to delete or remove. If you are unsure which one to delete, call your ISP tech support. They can walk you through this same process and examine each one.