They may not look alike, but Senate twins vote alike. Senators from 22 states had composite scores within 5 percentage points of each other, in National Journal's 2010 vote ratings.
Here are the top 10 pairs of Senate twins -- home-state senators who have composite scores within 1 point of each other.
Former Sen. Blanche Lincoln (D) and Sen. Mark Pryor (D) have the same composite scores. Lincoln and Pryor have the same score on foreign-policy issues but differ by 1 point on both economic and social issues.
Sens. Daniel Inouye (D) and Daniel Akaka (D) have identical composite scores, including the same rating on economic, social, and foreign-policy issues. Recently though, Inouye has expressed concerns about Akaka's commitment -- and chances -- in 2012.
Sens. James Risch (R) and Mike Crapo (R) both have the same composite scores. They're Senate twins for a second straight year -- they had a 5-point difference in composite score in National Journal's 2009 vote ratings.
Sens. Barbara Mikulski (D) and Ben Cardin (D) are evenly matched in composite scores. They grade out the same on economic, social, and foreign-policy issues.
Sens. Carl Levin (D) and Debbie Stabenow (D) have identical composite scores.
Sens. Kirsten Gillibrand (D) and Chuck Schumer (D) have a 0-point differential between their composite scores. They have the same scores on economic, social, and foreign-policy issues.
Sens. Patrick Leahy (D) and Bernie Sanders (I) have matching composite scores, as well as in each of National Journal's three categories.
Former Sen. Russell Feingold (D) and Sen. Herb Kohl (D) have a 0.1-point differential between their composite scores. In National Journal's 2009 vote ratings, Feingold and Kohl were considered a Senate odd couple with a 22.7-point difference in their composite scores.
Sens. Robert Menendez (D) and Frank Lautenberg (D) have a 0.4-point differential between their composite scores. Menendez and Lautenberg have the same score on social and foreign-policy issues, but their score on economic issues differs by 1 point.
Sens. Jon Tester (D) and Max Baucus (D) have a 1.0-point differential between their composite scores. They have the same score on social and foreign-policy issues but differ by 3 points on economic issues.