information about multiple certificates from client side

[Flavio Silva <flavioabs () gmail com>]

Hi all!

I am looking for some information about sites/companies/references
which forces the clients to use multiple certificates to access
servers or websites.
If someone works in such situation, I want to know the reasons to do
that, and if it is interesting for a provider, or web store.
Thank you for any help.

Best regards
-- 
Flavio A. Braga da Silva
Informatics Department
State University of Maringá (UEM)

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