Given that a score is generated based on data in a report any data in a report affects a given score. However, the impact of the accounts depends on the specifics of the accounts -- consider the standard factors:
http://www.myfico.com/crediteducation/whatsinyourscore.aspx
Number of accounts itself generally doesn't mean much. It does play a part in Average Age of Accounts (Length of Credit History) and may give a slight edge with a higher number of accounts indicating that the consumer is trusted by creditors. However, I wouldn't recommend fixating solely on number of accounts.
You first need to verify which accounts are valid and active and which ones are not. You should already have some idea of what revolving accounts you hold and can use that information (open date, limit, last reported balance, etc) if the masked account number does not match the account numbers that you are familiar with. You may need to contact each creditor if that isn't sufficient to determine which accounts are valid. It is possible in some cases for a tradeline to show up multiple times but generally the non-active instance should be reported as closed. It's certainly also possible that some of those accounts were not opened by you. This is one major reason why you need to know your credit profile and routinely review your reports. Once you get things figured out you need to see about getting your creditors to report any required corrections.
I'd suggest going straight to the sources and pulling your reports directly from each CRA. The Annual Credit Report site would work as it really just redirects you to each CRA.
