The following is an excerpt from Dr. Thomas Holland's Crowned With Glory, ©2000, used with permission.
2 Peter 1:1 - "of God and our Saviour Jesus Christ"
"Simon Peter, a servant and an apostle of Jesus Christ, to them that have obtained like precious faith with us through the righteousness of God and our Saviour Jesus Christ:"
The Authorized Version has been accused of inconsistency in its translation of 2 Peter 1:1 when compared with its translation of 2 Peter 1:11. In the later passage we read, "For so an entrance shall be ministered unto you abundantly into the everlasting kingdom of our Lord and Saviour Jesus Christ."In making such an accusation, some have provided the following comparison between 2 Peter 1:1 and 2 Peter 1:11.
1:1: tou theou emon kai soteros Iesou Christou
1:11: tou kuriou emon kai soteros Iesou Christou
It is then noted that the only difference between the two verses is the substitution of kuriou (Lord) in verse eleven instead of theou (God) as found in verse one. Therefore, according to the Greek, verse one must be translated as "our God and Savior" in order to be consistent.  Since the KJV does not do this, it is looked upon as mistranslating this passage.
The point is well taken, and would be correct if the Greek text that underlies the KJV read as presented. However, it does not. The Greek text used by the King James translators was Beza's text of 1589 and 1598. There we find an additional emon (our) at 2 Peter 1:1 that is not provided by those who call this a mistranslation. The two are compared below with Beza's text presented first.
Tou theou emon kai soteros emon Iesou Christou
Tou theou emon kai soteros Iesou Christou
The translation of Beza's text is correct and consistent in the Authorized Version, and is consistent since the additional emon appears in 2 Peter 1:1 and not 2 Peter 1:11.
The question exists why Beza provided the additional emon at 2 Peter 1:1 that is not found in other Greek texts. Dr. Bruce Metzger may supply the answer. Although not discussing this passage, Dr. Metzger does note the following concerning Beza:
Accompanied by annotations and his own Latin version, as well as Jerome's Latin Vulgate, these editions (of Beza's text from 1565, 1582, 1589, and 1598) contained a certain amount of textual information drawn from several Greek manuscripts which Beza had collated himself, as well as the Greek manuscripts collated by Henry Stephanus, son of Robert Stephanus. 
Since the Greek text of Robert Stephanus did not contain the addition, and the Greek text of Beza does, it is logical to assume that Beza added the emon at 2 Peter 1:1 based on the various manuscripts that he possessed (or the ones possessed by Henry Stephanus). We would be mistaken to presume that all existing manuscripts used in the sixteenth century are still in existence today. Some have undoubtedly passed away over the process of time. Regardless, the inclusion of the extra emon in this passage provides evidence of its preservation. It is certainly not a mistranslation on the part of the KJV.
 White, 268.
 Metzger, The Text Of The New Testament, 105.