two domain names for the same site

[awebguy]

Currently I have two domain names that point to the same site. One of them is a free Yahoo Geocities domain, and another one is my personal domain which I registered a few days ago.

A part of my site is indexed by googlebot with old domain name and another part of my site is indexed with new domain name. Some of my pages are indexed with two domain names, old and new.
Certainly, I have only one site and both domain names point to the same set of web pages.

Do you consider such a situation as a duplicate content or another drawback that may influence the ranking of my web pages in the Googles SERPs?