Professor put me in cc when sending recommendation letter to college I am applying to?
It is becoming more widely accepted that people have the right to be aware which information is kept on them by various organisations, to request access to this information and in some cases to request this information to be deleted (see e.g. FOI for UK, GDPR for EU). So by cc'ing you in, you professor acknowledged your right to access the same information about yourself that (s)he is sharing with the third party.

No, it does not reduce your chances &mdash; it is perfectly reasonable for professor  to show the recommendation letter to the candidate, if they wanted to, and in some places it is even required.