In the process of my ongoing investigations and inquiries of legislative ideological behavior, I have found a stumbling block in looking at the data. There are naturally some errors. These usually involve mixing names with votes. For instance, if two members of a Congress have the last name Brown there is a chance that there will be an error in vote tabulation. This has happened more than once, by the way. While I think both voteview.org through UCLA and Govtrack are useful and accessible resources, they both have these errors contained within. I determine an error based on what was recorded in the Congressional Record, which I regard as the ultimate primary source for Congress. I of course have not found all errors, but these are ones I have stumbled on so far in trying to create ratings for the MC-Index:

74th Congress: John Robsion’s (R-Ky.) and A. Willis Robertson’s (D-Va.) votes are swapped on overriding President Roosevelt’s veto of the 1936 veterans bonus bill on January 24, 1936. Robsion voted “yea” while Robertson voted “nay”.

79th Congress: William Lemke’s (R-N.D.) and Charles Robertson’s (R-N.D.) votes are swapped.

81st Congress: William P. Bolton (D-Md.) and Frances Bolton (R-Ohio) are swapped on the votes on striking public housing from the 1949 housing bill, recommitting the housing bill, and the bill itself. Bolton (D-Md.) opposed public housing and Bolton (R-Ohio) favored. These were all held on June 29, 1949.

Representatives Edgar Jonas (R-Ill.) and Ben Jensen (R-Iowa) are mistakenly marked as “yea” for the Far Eastern Assistance Act in 1950 while Representatives J. Leroy Johnson (R-Calif.) and Walter Judd (R-Minn.) are mistakenly marked as “nay”. This vote was held on February 9, 1950.

On the votes on FEPC, Representatives J. Caleb Boggs (R-Del.) and Hale Boggs (D-La.) are swapped on both the McConnell Amendment and final passage. John Phillips (R-Calif.) and Dayton Phillips (R-Tenn.) are swapped on final passage. Fred Crawford (R-Mich.) is mistakenly marked as “nay” on the McConnell Amendment to the FEPC while William J. Green (D-Penn.) and Robert Corbett (R-Penn.) are mistakenly marked as “yea”. These votes were held on February 22, 1950.

89th Congress: Senators Milward Simpson (R-Wyo.) and Hugh Scott (R-Penn.) are swapped on the Fair Labor Standards Act Amendments of 1966 final vote on August 26, 1966. Simpson, who was arch-conservative, paired against, and Scott, a moderate, voted for.
E. Ross Adair (R-Ind.) and Watkins Abbitt (D-Va.) are swapped on the conference report of the Voting Rights Act of 1965 on August 3, 1965. Adair voted for while Abbitt voted against.

90th Congress: George Brown (D-Calif.) and Clarence Brown (R-Ohio) are mixed up on the Wyman (R-N.H.) amendment denying funding for students participating in certain demonstrations on college campuses, May 9, 1968. Brown (R-Ohio) voted for the amendment, and Brown (D-Calif.) voted against.

91st Congress: Alabama Democrats George W. Andrews, Tom Bevill, and Walter Flowers did NOT favor retention of the Philadelphia Plan. The vote was on December 23, 1969.

92nd Congress:

George P. Miller (D-Calif.) and Clarence E. Miller (R-Ohio) are mixed up on the Hathaway (D-Me.) amendment to the education appropriations bill increasing funds by $728.6 million. California’s Miller supported, Ohio’s Miller opposed. The vote is on April 7, 1971.
Jack Edwards (R-Ala.) and Don Edwards (D-Calif.) switch on 1972 proposed 5% defense cut from Don Riegle (R-Mich.) on September 14, 1972.

93rd Congress: Garry Brown (R-Mich.) and Clarence Brown (R-Ohio) votes are swapped for the whole Congress and John W. Stanton’s (R-Ohio) and James V. Stanton’s (D-Ohio) are swapped for 1974; Robert Bauman’s and Alphonzo Bell’s are also mixed up in 1974.

Senators Barry Goldwater (R-Ariz.) and J. William Fulbright (D-Ark.) switched on Rhodesia sanctions. Goldwater voted AGAINST and Fulbright voted FOR sanctions for Rhodesia on December 18, 1973.

94th Congress: Representatives Barbara Collins (D-Ill.) and Jim Collins (R-Tex.) switched on Stratton Amendment permitting women to join military academies, May 20, 1975.

95th Congress: Hamilton Fish (R-N.Y.) and Joseph Fisher (D-Va.) are swapped on the February 8, 1978 vote on the proposed Consumer Protection Act.

98th Congress: The vote on the Civil Rights Act of 1984 on June 26, 1984 in the House counts absences as votes against.